Does “ADDING” Zinc to low zinc oils really help?
This write-up ended up being very long, so if you don’t want to bother with something quite long, then feel free to close out now and go on to the next topic.
The Diesel oil “wear testing” (or Diesel oil “film strength testing”, if you prefer) effort I have coming up, has become fairly sizable, so it will be quite some time before it’s ready to share. In the meantime, I thought I’d do this zinc additive test since it would take far less time, and would be every bit as interesting. My apologies for this write-up being so long, because before I get into this test, I need to address a few questions that seem to keep coming up regarding this “wear testing”. That way, hopefully we can all be on the same page.
THE TESTER USED:
If someone shows up at your shop or puts on some kind of demonstration promoting some type of lubricant and pulls out one of those "one armed bandit" oil testers, with a torque wrench on it. Send him away or walk away before he wastes your time. Those one armed bandits were designed to hype a lubrication product, and can be very easily manipulated by how you apply the load. You can make the same oil look good or bad, depending on how “fast and abrupt” or “slow and easy” you apply that load. It is pure snake oil.
As for the testing I did for this thread, I specifically did NOT purchase one of those "one armed bandit" testers. With my tester, you have to apply small individual weights, one at a time, so as to gradually apply the load and not shock load the oil being tested. I perform every test "exactly the same", as much as humanly possible, while being extremely careful. Then to allow for minor variations, I perform multiple tests of each oil, and average all those results to arrive at the final posted value. But, even before I average those values, the testing I perform is so close to identical, that the variation between results is typically within 2 to 5%, which is quite good. And that clearly shows how all these oils compare head to head.
FOCUSING ON FILM STRENGTH:
My tester focuses on an oil’s “load carrying capability or film strength”, and for good reason. “THE” single most “CRITICAL” capability of any motor oil is its film strength. Every thing else it does for your engine comes “AFTER” that. Here’s why. When oil is down to a very thin film, it is the last line of defense against metal to metal contact and subsequent wear or damage. And oil film strength capability “DIRECTLY APPLIES” to flat tappet lobe/lifter interfaces, cam gear/distributor gear interfaces, and other highly loaded engine component interfaces. The higher an oil’s film strength, the better protected your engine is in these areas.
Oil film strength capability also “DIRECTLY APPLIES” to cold start-up conditions. In this case, only an oil film remains on most internal engine components, because most of the oil drained off after shut down. And it’s no secret that nearly all wear occurs during start-up when there can be a couple of seconds or even more, depending on the viscosity being used and the ambient air temperature, before a flow of oil reaches all the components. Before oil flow reaches the components, all you have saving your engine from wear or damage, is the oil’s film strength. So, that’s another very important reason why it’s beneficial to use an oil with an excellent film strength.
When Amsoil refers to wear scar size comparisons on their website, they are referencing oil film strength test data. A couple of years or so ago, when Castrol Edge and Valvoline SynPower ads talked about their oils providing better wear protection than Mobil 1, they were referencing oil film strength test data. Pennzoil Ultra currently advertises that no leading synthetic oil provides better wear protection, and they also reference oil film strength test data. The bottom line is that oil film strength testing and the resulting data, is the gold standard in the motor oil industry, regarding wear protection.
There is no additional value to performing more “comprehensive” oil testing related to wear prevention. Because when an oil is thicker than a mere film, it becomes “liquid” oil. And all liquids are incompressible, which of course is how hydraulics work. Since liquid oil is “NOT” compressible, where parts are separated by a flow of liquid oil, you “cannot” have metal to metal contact. For example, the oil between the crank and rod or main bearings, is "liquid" oil. And the "liquid" oil in that hydrodynamic wedge is incompressible, just like any liquid is. So, there is no need for any testing of a liquid oil condition, because incompressible liquids is just common knowledge in Physics.
And if conditions cause the flow of liquid oil to be squeezed out of the way, you are right back to being left with only an oil film, and the need for good film strength. To achieve metal to metal contact, and thus wear/damage, you have to go through the oil’s film strength to get there. And since liquid oil “CANNOT” be compressed, that means that “ALL” oils when in liquid form, provide the “SAME” level of wear protection. And this is “PRECISELY” why we perform “FILM STRENGTH” testing. Because the only thing that separates one oil from another oil, in terms of wear prevention, is the difference between their film strength capabilities. So, if an oil has sufficient film strength capability, then you are good to go when it comes to wear prevention.
My testing performs severe torture testing on motor oil, which is much harder on the oil, than what the oil will ever experience inside any running engine. This is a dynamic friction test under load, and the test results are determined by the size of the wear scar. And how good an oil is at preventing wear, high zinc or low zinc, is determined in a fair and straight forward manner. The numbers come out how they come out, depending on the capability of the oil.
All of the oils are tested at a representative normal operating oil temperature of 230*F, to make the comparison meaningful. By testing in this manner, it absolutely shows which oils are better at preventing wear than others. This is NOT Rocket Science. But, it is a real world test comparison. This type of testing allows you to test a multitude of oils EXACTLY THE SAME, under controlled and repeatable conditions, which you simply cannot do in a running engine. And you can see how they compare right away, without having to wait for 100,000 miles to find out what happened. With this testing methodology, you can quickly and easily distinguish between outstanding oils and merely ordinary oils.
NOTE: A motor oil’s “load carrying capacity/film strength” capability is NOT the same thing as slipperiness or friction reduction. Therefore, this type of test data says nothing at all about the amount of Horsepower one oil will make vs another.
HIGH ZINC OILS VS LOW ZINC OILS:
Zinc is used as an extreme pressure, anti-wear additive, as most everyone knows. But, zinc “DOES NOT” build-up over time like some type of plating process. For those who have actually taken an engine apart that has been running high zinc oil, you know that you don’t find a build-up of zinc that looks like some sort of coating or sludge build-up. Zinc doesn’t work that way. And zinc is not even a lubricant until heat and load are applied. Zinc is only used when there is actual metal to metal contact in the engine. At that point zinc must react with the heat and load to create the sacrificial film that allows it to protect flat-tappet camshafts and other highly loaded engine parts. So, with zinc being sacrificial, it will become depleted over time as it is used up. This has been confirmed by analysis of new and used oil lab testing. And the literature from the “ZDDPlus” zinc additive folks also says the exact same thing, if you’d like to verify it there.
“Lab Testing” and “Wear Testing” analysis also shows that extra zinc does NOT provide BETTER wear protection, it only provides LONGER wear protection. This is not a new discovery at all. In fact, for what it’s worth, Ed Hackett wrote an article some years ago, titled “More than you ever wanted to know about Motor Oil”. And in that article he says the exact same thing, so it’s been well known for a long time. You can Google his article if you like, and see for yourself. And excessively HIGH zinc content can lead to INCREASED wear, due to its abrasive nature at high levels. There is such a thing as too much of a good thing.
So, you really don’t want or need a ton of zinc. You simply need “enough” so that you don’t run out of it with your particular application, that’s all. And this is precisely the reason why the motor oil “wear testing” I’ve been performing, has shown that the LEVEL of zinc does not affect how well an oil can provide wear protection. I’ve had many high zinc oils, as well as many low zinc oils, produce outstanding results in the wear testing. And I’ve also had high zinc oils as well as low zinc oils produce only modest results in the wear testing. Wear protection is determined only by the base oil and its additive package “as a whole”, and NOT just by how much zinc is present.
Modern API certified oils use alternate chemistry that is equal to, or better than zinc/phos, to replace much of the zinc/phos that might otherwise be used in those oils, so that the cats are not fouled in modern street vehicles. And most modern API SM and SN certified oils have shown in my wear testing to be quite good when it comes to providing wear protection.
LAB WEAR TESTING VS ENGINE WEAR TESTING:
It is essentially impossible to test dozens and dozens of oils inside a running engine with 100% identical conditions. And imagine how difficult it would be to remove every single drop of oil from inside an engine before you test the next oil. Because of course, any residual oil remaining would contaminate the next oil and skew the results for it. It would take a tear down between every oil test to ensure that there was absolutely no residual oil left.
Plus, you'd have tear the engine down anyway to blueprint it every time, in order to see how much wear took place. But, how many miles would you have to put on it to be sure you'd tested enough? How long do you think that would take when testing 50 or 60 different oils? A number of years, right? By then, some of the oils wouldn't even be available anymore. And then you'd also have to test the engine under the "exact same" conditions time after time, after time, which is basically impossible. So, the idea of accurately testing this many oils inside a running engine is completely out of the question.
The tester used here, was never intended to reflect exactly what goes on inside a running engine. It was designed to test “oil against oil”, nothing else. So, the whole point of my lab “wear testing” was to test oils directly against each other, head to head, back to back. Then see how they stacked up against each other. For example, if oil "A" has a 110,000 psi capability in this test, and oil "B" has only a 65,000 psi capability in this test, it’s not hard to understand the fact that oil "A" will provide a much higher level of reserve wear protection in a running engine as well.
But, keep in mind that I've never ever said that I found any BAD oils. Because I did NOT find any bad oils. Even the lowest ranked oil will still generally perform well enough in most applications. And that is precisely why you could have had an oil that has always worked well inside a running engine, yet find that it ranked only mid-pack, or even lower in this testing. However, like I said, “lower ranking” oils will not provide as much reserve wear protection as “higher ranking” oils.
The whole thing simply comes down to what is called "margin of safety" or extra reserve protection capability. Let's say the lowest ranked oil has a 20% margin of safety relative to your engine's needs, which means that the oil’s capability "exceeds" your engine's needs by 20%. So, you are in good shape and you will never see a problem. But, if something bad happens like an overheating condition, or an oiling condition, or a loading condition, or some parts heading south, or whatever, and your oil protection requirements increase to say 50% above your engine’s typical needs. Now you've just exceeded the oil’s capability by a whopping 30%, and your engine is junk. But, what if you'd been running an oil that had a whopping 70% margin of safety to begin with. In this case, when your engine’s needs went up 50%, but you still have another 20% capability above that. So, your engine would still live to fight another day.
It all comes down to how much margin of safety an individual is comfortable with for his particular engine combo. I'm one of those guys who runs a block, crank, pistons, rods, etc, that are capable of handling WAY more power than my weenie 800ish HP, 540 BBC will ever make. I simply feel better about having a LARGE margin of safety everywhere I can. And I'm the same way when it comes to the oil I run. So, I've chosen the oil with the highest wear protection capability, even though the oil with the lowest capability might work well enough under most circumstances. And that's whole point of all my oil testing, having the data to make an informed choice when it comes to choosing the best motor oil.
I did all this testing only for my own knowledge, because there is so much misinformation and misunderstanding about motor oil. And some buddies talked me into sharing the info on some of the Forums. But, I do NOT sell oil, and I do NOT get paid by any oil company. So, it doesn't matter to me what oil people buy, or why they buy, the oil they buy. That being the case, I have absolutely no reason to try to make one oil seem better than another. On the contrary, I'm only interested in seeing how they TRULY differ.
There is no Snake Oil pitch going on here. And I'm not trying to convince anyone of anything, I'm only sharing my findings. People can embrace my data or ignore it. It really doesn't matter to me. So, run whatever oil you like, but now you’ll have the data to see how oils rank, relative to each other.
So finally, on with the AFTERMARKET ZINC ADDITIVE TEST.
The motor oil companies have always insisted that we “NEVER EVER” add anything to their oil, because adding “ANYTHING” to it, will upset the carefully balanced additive package that they painstakingly designed for each of their oil products. And adding anything will only make the oil “WORSE” than it was to begin with, by altering its chemical properties. These Chemical Engineers and Chemists know what they are doing and are the experts for their own products. But, I’m well aware that a number of folks are either not aware of this warning, or else they simply choose to ignore it and use aftermarket oil additives anyway. They have no doubt been brainwashed by the high zinc folklore and figure they can do better than the motor oil companies themselves.
I thought it would be interesting to see who was right about all this. So, I selected the lowest ranked, low zinc oil from my previous “wear testing”, which was the Motorcraft 5W30, API SN full synthetic oil. It ranked 45th out of the 48 oils I’d tested so far, with a 68,782 psi “load carrying capacity/film strength” value, which put it in the “Modest Protection” category. I figured since this low zinc oil needed the most help, that it would show the clearest difference of all the oils on hand.
I also selected two aftermarket zinc additives to test in that oil. One was “ZDDPlus”, and the other was “Edelbrock Zinc Additive”. Not only would I be testing zinc additives in general, but I’d also be testing these two zinc products against each other, to see how they compared.
The Royal Purple Engineers I’ve spoken with, told me that the technology is not in place to ensure that every single batch of oil will be identical. So, if various bottles of otherwise identical oils are lab tested, they may well show different component amounts.
I wanted to add the appropriate amount of each zinc additive to its own bottle of oil, so I got two “NEW” bottles of the Motorcraft 5W30. But knowing that there can be variations between motor oil batches, I wanted to make sure that both bottles were absolutely identical. So, I poured both bottles into a clean pan, thoroughly mixed them, and poured them back into the bottles. Now I had two identical bottles of Motorcraft 5W30, API SN.
I sent a sample of this newly mixed and matched oil into to the lab for testing. That way, I could see exactly how this oil started out, to use that as a baseline for comparison. I also “wear tested” it again in this current configuration in order to know its actual “load carrying capacity/film strength” to use that as a baseline for comparison as well. The details are just below.
Once all that had been established, then I added the appropriate amount of each zinc additive to its own bottle of oil, thoroughly shook them, and sent a sample of each into the lab for testing. So, I’d be able to see exactly how each zinc additive had changed the make-up of the oil. Then finally, I was ready to perform the wear tests on each bottle of oil, to see how each type of zinc additive may have changed the oil’s wear prevention capability. Here’s the comparison:
Motorcraft 5W30, API SN, full synthetic, factory baseline version (from the two factory bottles mixed together):
Zinc = 1107 ppm
Phos = 758 ppm
Moly = 74 ppm
After repeated testing, the “load carrying capacity/film strength” = 64,166 psi at 230*F, which is the baseline for comparison to the oils below that have the zinc additives.
Motorcraft 5W30, API SN, full synthetic, now with the appropriate amount of “ZDDPlus” added:
Zinc = 2955 ppm (up 1848 ppm)
Phos = 2114 ppm (up 1356 ppm)
Moly = 76 ppm (up 2 ppm)
After repeated testing, the “load carrying capacity/film strength” = 56,243 psi at 230*F
YIKES!!! This is about 12% “BELOW” the factory baseline value above. In the ZDDPlus literature that comes with the bottles, it says that most motor oil additives are nothing more than automotive snake oil. So, it’s a bit ironic that their product appears to fall into the same category they were putting down.
Now, let’s take a look at the other zinc additive and see what it shows.
Motorcraft 5W30, API SN, full synthetic, now with the appropriate amount of “Edelbrock Zinc Additive” added:
Zinc = 1680 ppm (up 573 ppm)
Phos = 1275 ppm (up 517 ppm)
Moly = 89 ppm (up 15 ppm)
After repeated testing, the “load carrying capacity/film strength” = 50,202 psi at 230*F
This is about 22% “BELOW” the factory baseline value above.
And keep in mind, that with my test procedure and equipment, having a resulting value below 60,000 psi, puts an oil into the weak UNDESIRABLE protection category.
WOW!!! I honestly didn’t see that coming. I never expected that there would be such a large reduction in capability. I’ve seen in my earlier testing that higher zinc levels did not equal higher protection levels. And I know the oil companies say that adding anything to their oils will only ruin them. But, I thought there might only be a little actual difference in capability, not such a “HUGE” drop.
Obviously the oil companies “DO KNOW” what they are talking about, and were right all along. And at the same time, this also gives my test equipment and test procedure some credibility, since my results exactly reflect what the oil companies have always said.
And no one can complain that my test equipment and test procedure do not allow high zinc oils to perform at their highest level. Because here are some high zinc (over 1100 ppm) conventional, semi-synthetic, and full synthetic oils that I’ve tested previously. They all had test results over 90,000 psi, which put them in the “OUTSTANDING PROTECTION” category.
10W30 Lucas Racing Only, full synthetic = 106,505 psi
zinc = 2642 ppm
phos = 3489 ppm
moly = 1764 ppm
10W30 Valvoline NSL (Not Street Legal) Conventional Racing Oil = 103,846 psi
zinc = 1669 ppm
phos = 1518 ppm
moly = 784 ppm
10W30 Valvoline VR1 Conventional Racing Oil (silver bottle) = 103,505 psi
zinc = 1472 ppm
phos = 1544 ppm
10W30 Valvoline VR1 Synthetic Racing Oil, API SL (black bottle) = 101,139 psi
zinc = 1180 ppm
phos = 1112 ppm
moly = 162 ppm
30 wt Red Line Race Oil, full synthetic = 96,470 psi
zinc = 2207 ppm
phos = 2052 ppm
moly = 1235 ppm
10W30 Amsoil Z-Rod Oil, full synthetic = 95,360 psi
zinc = 1431 ppm
phos = 1441 ppm
moly = 52 ppm
10W30 Quaker State Defy, API SL (semi-synthetic) = 90,226 psi
zinc = 1221 ppm
phos = 955 ppm
moly = 99 ppm
To provide the most honest, fair and accurate results possible, I thought I should make sure that my test equipment was still performing as it should. Call it a calibration check. So, I decided to dig out the original bottle of Motorcraft 5W30, API SN, full synthetic that I had tested months ago, which had its test results posted in my original “wear test” write-up. Up to now, that particular bottle had NOT been involved in this zinc additive testing.
The plan was to re-test this oil and see if it still matched up to its original values from several months ago. If the results did match up, within the normal range of 2 to 5% variation, then it would show that the tester was still performing up to par, and that those zinc additive test results were valid.
This oil’s original posted value had been 68,782 psi. Now, after several months and dozens and dozens of oil tests later, repeated testing shows its resulting value as 66,664 psi. This value only differs by 3% from the original posted value, which is quite good. And it is smack in the middle of the normal variation range, indicating that the test equipment is still spot on. So, that leaves us with those poor zinc additive test results being correct.
But, not wanting to base the whole wind-up on testing with only a single oil, I decided to test each zinc additive with two additional oils. That would ultimately test each additive with 3 different oils, which would absolutely tell the tale without any question. I had selected this first Motorcraft oil from the “Modest Protection” category. This time I decided to select one oil from the “Good Protection” category, and one oil from the “Outstanding Protection” category, for each zinc additive. And I’d include both conventional and full synthetic oils. That way, the zinc additives would have every opportunity to perform across a full range of oils.
For reference, the Oil categories are:
*** Over 90,000 psi = OUTSTANDING protection
*** 75,000 to 90,000 psi = GOOD protection
*** 60,000 to 75,000 psi = MODEST protection
*** Below 60,000 psi = UNDESIRABLE protection
The “ZDDPlus” zinc additive will now also be tested in the following two oils:
Royal Purple 20W50, API SN, full synthetic, factory baseline version:
Zinc = 588 ppm
Phos = 697 ppm
Moly = 0 ppm
The original posted “load carrying capacity/film strength” = 83,487 psi at 230*F, and was ranked 34th out of 48 oils tested, which put it in the “Good Protection” category.
Royal Purple 20W50, API SN, full synthetic, now with the appropriate amount of “ZDDPlus” added:
Zinc = 2436 ppm
Phos = 2053 ppm
Moly = 2 ppm
After repeated testing, the “load carrying capacity/film strength” = 63,595 psi at 230*F
This is about 24% “BELOW” the factory baseline value just above. But, at least it is still in the “Modest Protection” category.
O’Reilly (house brand) 5W30, API SN, conventional, factory baseline version:
Zinc = 863 ppm
Phos = 816 ppm
Moly = 0 ppm
The original posted “load carrying capacity/film strength” = 91,433 psi at 230*F, and was ranked 25th out of 48 oils tested, which put it in the “Outstanding Protection” category.
O’Reilly (house brand) 5W30, API SN, conventional, now with the appropriate amount of “ZDDPlus” added:
Zinc = 2711 ppm
Phos = 2172 ppm
Moly = 2 ppm
After repeated testing, the “load carrying capacity/film strength” = 56,728 psi at 230*F
This is about 38% “BELOW” the factory baseline value just above.
So, there is nothing new after testing “ZDDPlus” in two additional oils.
Now let’s see how “Edelbrock Zinc Additive” does when also tested in two additional oils:
Royal Purple 5W30, API SN, full synthetic, factory baseline version:
Zinc = 942 ppm
Phos = 817 ppm
Moly = 0 ppm
The original posted “load carrying capacity/film strength” = 84,009 psi at 230*F, and was ranked 33rd out of 48 oils tested, which put it in the “Good Protection” category.
Royal Purple 5W30, API SN, full synthetic, now with the appropriate amount of “Edelbrock Zinc Additive” added:
Zinc = 1515 ppm
Phos = 1334 ppm
Moly = 15 ppm
After repeated testing, the “load carrying capacity/film strength” = 54,044 psi at 230*F
This is about 36% “BELOW” the factory baseline value just above.
Lucas 5W30, API SN, conventional, factory baseline version:
Zinc = 992 ppm
Phos = 760 ppm
Moly = 0 ppm
The original posted “load carrying capacity/film strength” = 92,073 psi at 230*F, and was ranked 24th out of 48 oils tested, which put it in the “Outstanding Protection” category.
Lucas 5W30, API SN, conventional, now with the appropriate amount of “Edelbrock Zinc Additive” added:
Zinc = 1565 ppm
Phos = 1277 ppm
Moly = 15 ppm
After repeated testing, the “load carrying capacity/film strength” = 51,545 psi at 230*F
This is about 44% “BELOW” the factory baseline value just above.
So, there is nothing new here either, after testing “Edelbrock Zinc Additive” in two additional oils.
The “ZDDPlus” aftermarket zinc additive was tested in the 3 following oils:
O’Reilly (house brand) 5W30, API SN, conventional
With the resulting wear protection level falling 38% “BELOW” the original factory oil
Motorcraft 5W30, API SN, full synthetic
With the resulting wear protection level falling 12% “BELOW” the original factory oil
Royal Purple 20W50, API SN, full synthetic
With the resulting wear protection level falling 24% “BELOW” the original factory oil
Taking into account all 3 oils, the average “DROP” in protection level was about 25%. So, there is sadly nothing good to report here.
The “Edelbrock Zinc Additive” aftermarket zinc additive was tested in the 3 following oils:
Motorcraft 5W30, API SN, full synthetic
With the resulting wear protection level falling 22% “BELOW” the original factory oil
Lucas 5W30, API SN, conventional
With the resulting wear protection level falling 44% “BELOW” the original factory oil
Royal Purple 5W30, API SN, full synthetic, API SN, full synthetic
With the resulting wear protection level falling 36% “BELOW” the original factory oil
Taking into account all 3 oils, the average “DROP” in protection level was 34%. So, there is nothing good to report here either.
There is no point in even attempting to declare a winner between these two aftermarket zinc additives. Because, even though one is less bad than the other, they are both clearly awful.
The test results above, prove beyond any shadow of a doubt, that the motor oil companies are absolutely correct when they say that you should NEVER EVER add anything to their carefully balanced additive packages, because you will only make the oil WORSE by ruining its chemical properties.
Those who have used these or other additives over the years without causing engine damage, no doubt wonder why, considering the test data above. The answer is easy. As long as an engine’s demands on its oil, DO NOT EXCEED the oil’s “load carrying capacity/film strength”, then there will be no engine damage. It’s that simple. But, using an additive such as the ones tested here, will certainly REDUCE an oils reserve wear protection capability, or its margin of safety, which is just the opposite of what was surely intended. And that puts you CLOSER to engine failure than you would have been, if you hadn’t added anything to the oil in the first place.
What that means of course is that, the low zinc oil you were using, which was weakened by the aftermarket zinc additive, was actually still good enough to keep your engine running “IN SPITE” of that added zinc, not “BECAUSE” of that added zinc. And in the process, you’ve actually made a case for how good those low zinc oils are to begin with.
And that matches up exactly with the test results I’ve been seeing all along, which have shown that most of the latest low zinc oils are generally quite good. And has also shown that the “LEVEL” of zinc does not determine how good an oil is at preventing wear. How good an oil is at preventing wear is determined by its base oil and its factory additive package “as a whole”, and NOT just by how much zinc is present.
You can only tell how good an oil is at preventing wear, by performing some type of dynamic “wear testing” (or film strength testing, if you prefer) at representative temperatures. If you only look at zinc levels from an oil’s spec sheet or lab print out, you will only be fooling yourself about how good a given oil is.
A few words about STP and Lucas oil treatments. I didn’t test these products added to a motor oil. So, I can’t say for sure how they would perform. However, based on my past experience with STP as an assembly lube, I expect it absolutely would show an increase in “load carrying capacity/film strength”. But, it does have a couple of downsides that override any increase in wear protection. It increases an oil’s viscosity which will reduce flow. And both STP and Lucas oil treatments have been known to cause increased foaming issues. Obviously it would be wise to avoid both of those concerns.
Most folks would no doubt like to have the highest level of protection possible from the oil they choose. So, don’t shoot yourself in the foot by adding something to your oil. Just select the best oil for your needs, and use it as is. There is an appropriate oil available for every conceivable combo out there.