Does anyone on board overfill their sump in preparation for track days or autocrosses? If so, what do you do and what have you noticed? I was always taught (likely incorrectly) that too much oil (never defined by quantity) was bad for the seals because it increased oil pressure dramatically. Thoughts?
And as an aside, at my local NAPA all weights of Royal Purple were under $10 a litre. Except for the one that I wanted to try (5W40), which was $13 a litre. Why would one weight be higher in price?
Too much oil will not increase your oil pressure but too much oil acts just like not enough. The crankshaft splashes around in the oil splash lubricating the underside of the pistons and the cylinder walls and the the discombobulation modulator. too much oil will foam it up real bad and aerate the oil. Since air is in the oil the volume of oil being pumped be reduced, and because air can be compressed the oil pressure will be reduced.
As far as overfilling for a track day, I have no experience, sorry.
Also, if you have a car with a turbo that drains low into the sump, you risk bringing the oil level up to the point where you'll inhibit the gravity drain under cornering and blow a mosquito-killing smokescreen.
race teams tend to underfill... (frees up some power) but then they have access to rebuilds whenever needed...
hey check it out.... full DORKTUM... didn't realize it had happened... a long long way to the next step...
paul
Reader
4/25/10 2:24 p.m.
Alot of the quad-cam mustang guys add a quart because the heads hold quite a bit of oil while the engine's running; and the pan has plenty of room for the extra quart otherwise.
I've heard this recommendation for a couple of cars - fill up to max or slightly above to ensure that the oil pump isn't sucking air in long corners.
Of course this advice would be much more useful if I could remember what car it was for.
It's a solid "it depends". Neons you want to underfill because they whip the oil at the full mark. 5-cylinder Audis you want to overfill, because they have an oil pan about four feet long and have less than four quarts in there and it's very easy to either suck the pan dry or slosh the oil away from the pickup.
I've seen people run 1.5 quarts over in a Subaru before with no ill effects. Of course, those engines have an incredibly deep sump as well. (about 8-10 inches below the crank)
In my S2000, I usually just fill it to the high mark (hot)
