[USMarine81]

My 69 has a crate LS-6 454 4 bolt main, steel forged rods, crank, and 10.2-1 pistons with rectangle HP heads. It has a lot of aftermarket additions like MSD ignition, weiland intake, hedman headers, holley 750, competition cam, and a NOS system. I bought it built and was told it put out about 450 HP regularly, and approx 600 w/ nitrous (rarely used).

My question is hopefully an easy one for this group: what engine oil should I use? What is the absolute best? Please also advise on the best weight (10W-40, 20W-50, 30W, 50W)as well. The engine is already fully broken in, and the car is driven only a few hard miles weekly. I live in Northern California, and the temps around here are never lower than 40 and often in the summer around 110.

I currently have Redline 50W racing oil in it. Seems to run ok, but the oil pressure never exceeds 55 psi or so, and at idle after running hard often dips down into the 20's. I also noticed on one of the oil bottles that it said "not recommended for street use." A guy who builds engines told me that 60 is a good psi. Any comments on this as well?

Thanks in advance for this great board.

[tom3]

The Redline racing is probably a low ash, low detergent oil, not that good for street use. The 20w50 might be the best for this. Lot of guys run Rotella T (Shell) oil in the 15w40 weight on high perf. engines around here. Your oil pressure sounds fine to me. I think you can also get Mobil 1 in the 15w40 weight, might be the perfect setup on an occasional driver. Little more power and less wear, more money though. tom

[mike brown]

in my ss 396 bored to 402 i went with mobil 1 15w50 and a mobil 1 filter after break-in. you can get the oil at wal mart for about $4.25/quart. the filter runs about $10 and i got mine at auto zone. one thing to keep in mind is the temp where you live. i'm in mississippi and it stays farily warm down here.

[GregGold]

I had a simular problem with mine a while back. After a few seconds at full throttle, the gauge would dip down to 20 or so. I installed a 7 quart oil pan and that did not help. I finally installed a set of oil restrictors in the back of the block. This ended the oil shortage. I think a mechanical cam is requred for the plugs.

[elcamino72]

I like Valvoline. I would say use 20w50.

[CHRIS SILVA]

Hi there as well as the right oil isn't a large aftermarket radiator a good idea, I have seen some that claim to lower temps by 40 degrees. After all heat is what kills most big blocks right?

[sr71bb]

Valvoline 20-50W should work fine. Change oil every 2500 miles. Synthetic is definitely NOT worth cost difference. It has NEVER been proven that a synthetic oil offers increased protection over non-synthetic as long as you adhere to frequent oil change intervals and as long as the engine is running in it's normal temperature range. As a matter of fact, Synthetic OIL SHOULD NEVER be used in a engine that hasn't been broken in yet.

Oil pressure sounds fine. My "NEW" 396 runs around 165 degrees and I have same oil pressure as you have.

Gheatly,

Edelbrock specifically states NOT to use synthetic before the CAM has a change to break-in. These instructions were included with the TORKER PLUS camshaft kit. Other camshaft manufacturers have similar warnings. I know of NO domestic car manufacturer that ships their engines with synthetic oil. Sythetic oil certainly won't HURT an engine after breakin but as I said before the POSITIVE effects of using synthetic oil have not been proven and that is why car manufacturers reccomend the same oil change intervel for both synthetic and non-synthetic oil. These are the facts not my opinion.

Interestingly enough I have dynoed a car with non-synthetic oil in it and with synthetic oil in it. In theory if the sythetic had better lubrication properties then you should be able to see some type of measurable difference in power output due to lees internal friction. There was however NO difference in power output.

[This message has been edited by sr71bb (edited 12-13-99).]

Gheatly,
Great point about the roller cam. Piston rings don't really need to be "broke-in" like they used to in the past either.

[This message has been edited by sr71bb (edited 12-13-99).]

[USMarine81]

Thanks everyone for the great replies. Currently I am running Redline, who advertises to be the absolute best. I do know that they are the most expensive, at $9/qt. It's a full synthetic, listed at 50W. The bottle says "meets all of the specifications of a 15W50. I read elsewhere that Mobil-1 was the best. Bought some Mobil-1 15W50 at walmart, not tooooo expensive, at around $6 qt. Any further advice from the board?

[gheatly]

sr71bb - I think you are incorrect in your statement that synthetic oil should never be used in a new engine. However, it may be a matter of opinion amoung engine builders. I asked my engine builder this very question and he said to use whatever I wanted. He pointed out the fact that many new high performance cars come directly from the factory with Mobil 1 synthetic oil. That's what I went with.

sr71bb - I should given a few more facts. I am running a roller cam. Therefore, I didn't have the break-in period required of a flat tappet camshaft. The engine builder said that new cylinder honing techniques provide almost instant ring seating so that is not an issue either. As for factory use of synthetics, I believe there were certain model years of Corvettes that were shipped with Mobil 1 from the factory.


[This message has been edited by gheatly (edited 12-13-99).]

[Toby T.]

I run 10w30 valvoline with pro-lube after break in my 500hp supercharged small block. Oil pressures are dead on at all rpms and I change oil every 2000 to 2500 miles. Use of this heavy stuff to me just is too much and I leave it to the racers with big hp. Oil coolers and hd coolant radiators are important too.

[gheatly]

I agree with Toby T. I think 50 weight oil is too heavy for a street car. I also have a (dyno proven) 500 hp supercharged small block and I use Mobil 1 10w-30.

If you think about it, the heavier the oil, the more drag you will have on the reciprocating assembly because its harder to shed the heavier oil. More drag = less horsepower.

[Shawn]

I recently read an very good paper by a Red Line Oil representitive, and he had some very good answers to many of the questions regarding synthetic vs. non-synthetic oils. It was well informed and not a simple plug for Redline Racing Oil. One of the biggest differences between synthetic and regular oil is the molecular structure of a synthetic. A synthetic oil has molecules that are all the same size, where as regular petroleum based oil has several complex molecules of varying size. There is virtually no advantage to synthetic oil for the first few thousand miles, but this is where they diverge however. A normal oil goes through a countinuous breakdown, many of the larger molecules begin to break up and collect microscopic carbon particles. Some of the oil itself breaks down to it's original element - Carbon. The breakdown steadily increases the viscous friction of the oil. The reason oil changes are recommended every 2500-3000 miles or so is because this is typically how long it takes the oil to start breaking down and losing it's lubricating properties. Some of these smaller, broken molecules that are not trapped by even the best filters begin to cause wear. Synthetic however does not break down in the same fashion, the molecules remain intact for as many as 10,000 miles. In addition, since the synthetic molecules do not break apart, there is less wear than a normal oil because it is not breaking down into the simpler, non-lubricating types of molecules. They do not recommend running oil this long however, because synthetic oil will pick up other contamination and engine combustion byproducts just as normal oil will. One of the things they recommend is to use any good synthetic oil (not just redline) for about 6000 miles before changing, but change the oil filter half way at about 3000 miles. Even though this sounds like a long time, it makes sense if you think about it. The oil is not breaking down like normal oil, so it doesn't lose it's lubricating properties. The enemy is contamination from the rest of the engine. By changing the filter at 3000, you are addressing this issue. Their data showed that lubrication and cooling is not compromised in any way by doing this, and oil usage drops roughly in half because you are changing it half as often. In the big picture, cost will then be about the same as using a good "regular" oil, and the benefit is less dirty oil going back into the environment. I'm sure many of you disagree with the idea of running the same synthetic oil for 6000 miles, but it's hard to dispute the data with speculation and opinion. So some of you are right by saying that synthetics have no lubrication advantages over normal oil, but that's only true to a point. Once the oils reach the 1000 mile range(depending on the engine) is where the synthetics shine. Provided with a filter change, they can last much longer.

My $.02 Chemistry lesson...


------------------
Shawn Peterson
1969 Z28, 406SB

[This message has been edited by Shawn (edited 12-14-99).]

[will stefan]

Dont use quaker state or penzoil oil. they have a perafin wax additive (liquid ball berings). this stuff build up in motors, and has to effect lubrication. I pulled one old guys 305 with my uncle (ase certified,25 yrs at a dealship, hates fords), wich had only seen penziol since it was an new truck, the result was amazing. it was like hard carbon about 2in inches thick all around the llifters and partialy covering push rods. my uncle said its the perafin wax, and he has seen worse than that. if you cant tell if it has parafin in it call the company and ask.

also now at every dealership they have a new fushing system they recomend every year to extend engine life. they power flush the motor with heated cleaning solution, They garantee its safe on your motor,and it works good, I had my 6yr old 350 flushed 1 yr ago and my oil still looks cean, costed 100$.
they also have the same type flush for coolant, power steering,brakes and ac.

[Austin]

Hey Shawn I think that was more like $.25.
Good info