I'd bet most of the heat absorbed by the oil is done before the car leaves the lights. What's the oil temperature at the point the car launches off the line? Got to be more than 160F when it was first fired up. Just the fact that only about one sump volume cycle goes through the engine in a 7 second run means the heat absorbed from the actual run doesn't really come into play because the run is over before the sump volume gets another run through the engine. And dumping heat into the oil for only 7 seconds isn't going to raise the oil temperature instantly because of the whole thermal mass of the system.
Engine Masters (MotorTrend) Tests Oil Viscosity (Thickies Rejoice!)
- Thread starter RDY4WAR
- Start date
How much heat do the valve springs create?
So far we have the burn out, staging and sitting on the rev limiter for a few seconds. From what we’ve learned, rpm contributes more heat to the oil than load.
Engine load contributes more heat to the cooling system than the engine oil.
Just do a calculation of how much heat is required in 7 seconds of time to raise 7-8 quarts of oil from 160 to 200+ F. And also calculate how much heat rise there would be in 7 seconds time if that level of heat was applied. The amount of mass in 7-8 quarts of oil doesn't change temperature "instantly". Seven seconds of heat absorption isn't very long for anything with some thermal mass to react. The oil probably keeps heating up well after the car goes over the finish line because of the thermal mass lag. My point is that the oil temperature just can't change much over that 6.5-7 seconds the car is actually going down the track. And if basically only one sump's worth of oil volume is circulated through the engine during the actual run, then it doesn't matter much what the sump temperature was at the end of the run.
What I´d bet is for the given conditions for drag racing, whatever viscosity they are using is the one that produces the maximum horsepower for the run. That´s what they are looking for, and I´m sure this has been explored by them extensively. VERY little to do with a passenger vehicle´s operational profile. So I won´t be transferring any conclusions from it. But it is certainly fascinating!
I could see it being relative to car that's driven around the city a lot, with a lot of stoplight to stoplight driving, as the cylinders see a good bit of pressure during even part throttle acceleration. It could lose a minuscule amount of efficiency, but this is still splitting hairs. The main takeaway from it is that oil can and does act as a gasket and that ring seal can be effected by your choice of oil.
You results may vary.
