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:
This could go on forever
![](http://944-spec.org/944SPEC/components/com_kunena/template/default/images/emoticons/w00t.png)
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.