This could go on forever Go to 'bobistheoilguy' site and spend a week.

Used to use 50. Now use the lightest oil that maintains proper pressure (at proper temp). Pump has to move it around and heavier is harder to move. If the temp goes too high that's another issue and I fix that; rather than run 50 'just in case'. Eric's post has good numbers.

Now find that 40 maintains good numbers. Use Redline or Amsoil ('racing'). I've done oil analysis and while the vendors online won't generally express a preference privately on my analysis both Redline and Amsoil have been suggested.

Recently talked to a local shop that preps a lot of dirt track cars. They have experienced a real improvement in durability (they count laps) using Joe Gibbs stuff. Very pricey and I frankly don't think we work our motors as hard as theirs (are).

Short answer over the years I became absolutely convinced that we all were using too heavy an oil to make up for too high temps.

I agree, heavy oils are not 'safer' they are just that, heavier. A lighter weight oil will cool better than a heavy weight oil and will flow better and will take less power to run.

I run Brad Penn in my race engines. On the GT cars we would run 20, 30, or 40 strait grade oils. Of course those cars had oil heaters to bring the oil up to temp before we would hit the track. On the 944 I am planning to run a 5W30 or 10W30.

All of this being said, you do need to control the oil temps.

JB3 wrote:

Last engine I did - the current car - used 30 just to get it going. Ran fine but the pressures were lower than I wanted hot or cold. Admittedly it was NOT a premium oil just 10w30 dino. After 'break in' switch to 40 Redline and everything is where it should be. I know of at least one other 944 that is running 30. Tells me there is a difference on the dyno. But he also is willing to spend a LOT more $$. And does on a regular basis.

Interesting, I do seem to be slightly down on power compared to those in front of me so maybe I'll drop to 40wt.

I generally change oil every other weekend but not always. I've gone 4 weekends many times, and if I have a bad race, the car doesn't get out of the trailer until the day before the next event, and then it's only for a bath, because I'll be mad at it(clearly it is the car's fault, not mine if I lose!).

I don't know if it is all rebuilt 944's but I know the motors Autpoint build all seem to not dirty up the oil. In fact, there are times I can't read the dipstick it's so clean!

Before changing oil that often try $25 on oil analysis. Bet it's still perfect even after 4 weekends. That's what; 8 hours max?

I agree. I do oil analysis and the additive package with Redline 50WT has been good every time I checked. I run the oil for at least 1/2 season then have it analyzed. The oil itself would easily run a whole season, the problem I've had is high silica (dirt). After the last analysis, I replaced the oil fill cap o-ring which was hard as a rock and suggested as a source of the contamination (my air intake system is tight as far as I can tell). We'll see if it stays cleaner when I do another sample after the season.

Ron, I don't think the 50WT oil is slowing you down