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I read somewhere that synthetic oil attacks gaskets. I have been using a synthetic in our '95 Lumina and have noticed an oil seepage at lower part of engine. Synthetic may have nothing to do with this. Just wanted to hear about some of your experiences. Thanks
 

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Good quality synthetics do NOT attack gaskets or seals. That old wives tale came from the folks that had old gummed up engines with tons of miles on them using petro oil. The seals and gaskets developed minor cracks in them, but the oil varnished up under heat and more or less filled the cracks.
Syns come along with better detergent ability and cleaned out the petro varnish and the leaks came back. Just snug up your pan or valve cover bolts, they might be loose. If its a high mileage car, the above scenerio might apply and if it leaks too much, change the gaskets or try the old petro oils to plug em up again.
 

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Originally posted by jethro:
Anyway, lets get back to the subject at hand... some of the posts here previous have convinced me to run synthetics... I like Mobil 1, but what I'm still struggling with is the time between changes... I assume running a 327 in a 67 Camaro with a double pumper mechanical Demon carb means I have to have some kind of wash down cylinder walls occasionally, and is probably contaminating the crankcase more than say a fuel injected model... so...how often... is the same old standard 3000/3 months good?
 

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Jethro if gas does wash into your engine, as long as you are getting it HOT driving it, then most of that fuel should be burned off. If you really want to know whats going on inside your engine, have an oil anaylsis done on your next change. About $25. It will tell you if there is excessive gas present. If not, then extending your drain interval is ok. It will also alert you to wear of other engine parts like rings and bearings if there is any premature problem that is coming along.
If you REALLY want to get into oils and the science behind them, email me and I can give you a web site of engineers and chemists that really wack this topic around.

 

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Here is what I heard, and maybe it applies a little to your problem;
When synthetics were first developed by oil companies in partnerships with race teams (in Formula 1 I think it was) they immediately noticed a performance increase. The oil was simply slipperier than crude derivatives. But, since the engine was a stressed member in the car (made up part of the rear frame assy.) it was always stressed and moving slightly. Along with the higher horsepower there was a lot more oil leakage than before. It seemed that the more slippery fluid would find its way out of the engine just that much easier also. So, then there was a flurry of new gasketing technology. No way were the race teams going to give up the new-found horsepower over a few oil leaks!
So again I want to say this might be an old-wives tale. I'm sure there are engineers here that will know the true story for sure.
 

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Having been in a car club that had a lot of people using about every brand of synthethic oil, here is something that we found. On older engines, they would find more oil weeping then newer ones. The mainly was due to the older gaskets drying out. Once replaced, oil weepage was gone.

On a whole, we also found that Mobil 1 had a higher problem with leaks/weepage then any other oils. One guy who researched and dyno tested about every Syn. oil out found that the meclecular (sp?) makeup of Mobil 1 had smaller molicuals (sp?) and was more prone to leaks.

BTW, in back to back dyno testing he did, Royal Purple made the most HP at 7HP more then lowest one and 3 more then the next closest. Take it for what it's worth.
 

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When I was at AutoZone working, we got a flier about sunthetic use in older (70's, 80's to very early 90's) cars. It explained that conventional oils would soak into and swell a fiber gasket which is normal. When changing to synthetic, it did not soak in and swell the gaskets so they would dry out and shrink ever so slightly. This would cause a leak. Since then, gasket makers changed compositions a bit so both oils will work well in cars with the newer gaskets. Believe it or not
 

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A little more on seals, the syns have a 'seal swell' additive that promotes seal swell to keep them from shrinking and leaking. The syns of today are leap years ahead of the 70's syns as mentioned above.
Technology allows them build an oil to do just about anything but wash windows.
Dont worry about gaskets or seals in rebuilt engines or modern day cars. Works great.


subnote, some early syns had some poly ethelene glycol in their construction that actually 'ate' seals up. They quit that in the early 70's.
 

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Does anyone know what happens to syn oil in an engine that burns oil? Does carbon build up like with dino oil? Does it even build up deposits? Will it foul plugs?
My engine is getting a little tired, and has started to burn some oil, not lots but some, so i am wondering what would happen if I convert to Syn oil????

I already run Syn tranny fluid (Mobil 1) and am going to switch to Syn in the rear end.
 

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Okay, I will chime in with a few comments. I have studied this stuff for years writing a few articles on its content and use. Here's what I gleaned from my escapades!

First, there are real synthetics and fake synthetics. The real ones are like Mobile One, Amsoil, Redline, Royal Purple, and a few others. These are made from group IV and V base stocks. Others such as Valvoline, Havoline, Castrol etc are made from higher refined standard mineral stock Group III base stocks. Essentially a purer form of oil, but still share the same issues as regular oils.

Although the engineering of each synthetic base stock varies depending on the particular stock, synthetics are generally made through a reaction process. This reaction process significantly improves the consistency of the stock and its molecular uniformity. Mineral stocks, on the other hand, are obtained through a process of distillation.

Distillation slightly limits the molecular diversity that may exist within the stock , but does not completely eliminate nonessential molecular structures. This is important because unnecessary molecular structures produce variations in the stock's performance. The ideal lubricants chemical composition is one in which the molecular construction is identical throughout, such as in a synthetic base stock. Because of the way synthetic stocks are produced, they are molecularly uniform and contain significantly less undesirable materials than a mineral base stock.

So, first lesson....buy the good stuff and not the mineral stock junk. Mobile One is probabaly the best product for the money and is a real synthetic. MO comes in many OEM applications as well including Mercedes and Corvettes right from the factory.

Also, let's dispell the myths of synthetics. Even tho this article http://www.oilsandlube.com/myths.htm shows up on an Amsoil site, it was originally written by Ed Newman, an industry expert a few years ago.

My last diatribe is directed at Dennis and the 3000 mile oil changes. Question: Can you change your oil too frequently. Interestingly enough the answer is yes! The perverbial 3000 mile changeout is a product of the oil industries marketing department. Even all OEMs recommend at least a 7000 mile change under normal conditions! I would think all that R&D would have some credibility.

Moreover, oils are produced from birth with an alkyline content to offset the inherent acidity that comes with age and usage. The perfect acid/alkyline mixture range starts at about 3000 and goes to about 6000 miles in mineral based products and 3000 to 15000 miles in synthetics (synthetics and/or their by products do not combine with combustion by-products to form acids such as mineral based products). Why is this important to know? WE all know that acids attack iron and steel....conversely alky based products attack aluminum, copper, and other "soft" metals. So, if you are constantly bathing your parts in either, there is damage! So, 3000 mile oil changes are out unless you have other reasons to do it! I have seen staining on pistons as a result of this phenom.

So, the answer is with most mineral based oils is that 7000 miles is perfect for changeouts. On the other hand I have pushed synthetics (with testing) to 20,000 miles now safely on all my regular fleet, and usually change out my hotrods every two years which is around 12,000 miles. I have also dissected my NAPA Gold filters at these intervals and noted no significant damage or plugging to suggest any different ranges needed.

With Mobile One at $3 a quart at Walmart sales, an increase in gas milage....this easily makes synthetics a more economcial choice these days! ;)

[ 06-03-2004, 05:03 AM: Message edited by: HOTRODSRJ ]
 

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I don't understand the point you make about oil being to alkyline from the refinery and that it takes 3000 miles before the oil is neutral or heading towards the acidic side? Doesn't oil acidify as a result of direct contact with products of combustion? If so won't engines reach that point at different times, not just at 3000 miles. The point I am trying to understand is all engines are differnt in how much products of combustion reach the oil as some engines are tighter then others.
We use to run engine oil in large engines in an industrial setting, the oil was cleaned constantly through a cetrifuge type seperator. We would run the oil as long as the oil was not to acid. It usually took about 2 years of constant use and cleaning before the oil was dumped because of high acidty. The oil was tested biweekly for PH.
 

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Wayner...my point is that all mineral-based oils are made from the get-go as slightly alkyline PH right out of the can/bottle. They are NOT neutral! This is in anticipation of the combinations with moreover additives and combustion by-products that yes indeed form acids and attack metals as one drives etc.

Yes, all motors are not necessarily the same, but ranges of these are designed to cover 95% of the applications. As you may know, it's the collection of water in the crankcase that promotes this acid formation so driving short trips will also effect the longivity of the oil.

In independent testing and over a range of useage/applications, in general the "perfect" concoction of PH happens AFTER 3000 miles and will stay in range to about 7000 miles....again depending on driving habbits, environment and engines. But, what we do know is if you constantly change your oil and replace it with alkyline PH based products, the soft metals are being bathed in this over their entire lives....which they are NOT designed for nor is the oil per se designed for.

My main point is that even tho 3000 miles is probably no big deal, it's a waste of money to replace it then (unless you have conditions that dictate this for some reason) based on these issues.

Now..on synthetics....the PH is not as alky as the mineral based oils. The reason is that these synthetics will NOT mix with water and by products to produce the acids dino juice does. Therefore their life is longer!

While acidity is a paramount point in the aging of oil, there are other parameters as well that need to be followed to make sure the oil is effective for all applications. They are not mutually exclusive or inclusive for that matter. This has to do with film/shear strength (oil molecules actually get sheared!), thinning and evaporation, additive packages, particulate population and etc. So, acidity alone should never be the ultimate benchmark for changing oil per se.

Amsoil, which is one of the best in the world....both by company proclamation and independent testing, has reams of materials on all of this available on a plethora of websites. I suggest you search it and study up on synthetics. Once you understand the science and it's applications you will never go back!
 
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