Quote:
Originally Posted by Hags86
The answer is the thinnest possible oil that gives sufficient oil pressure. Get an oil pressure gauge.
This is a scatter plot of my car of oil pressures (Y axis) vs revs (X axis) where the colour is oil temp. The data is a shakedown run on my turbo setup, maybe 5 or 6 laps with just two hot laps. Stock bottom end, 0W-40 synthetic oil, 240rwkW on e85 with an oil cooler.
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Thanks, Hags for your very thorough reply! May I ask what brand/line of 0W-40 you were running?
I've been looking up specs on various oils, focusing mainly on the Viscosity numbers @ 100 deg C and @ 40 deg C. What I'm finding is there is quite a variance brand-to-brand within a given spec'd oil weight.
My thinking is that if 2 oils have a comparable viscosity at 40 deg C (meaning they will pump similarly when 'cold') the one with the higher viscosity at 100 deg C would maintain pressure better as temps increase.
I already have an oil cooler and oil temp gauge, but will now look at installing a pressure gauge as well. Finding a place to put it could be a bit of a challenge, though!