Originally Posted By: Doktor_Bert
Originally Posted By: ARCOgraphite
Your oil choices are absurdly thick and will lead to poor throttle response and loss of snappiness though Power above 5K rpm my only take a minor hit - if any once the oil is hot. You shouldn't need ANYTHING over a ACEA 30 grade. Just going form sa 20 to a 30 in the '01 bullitt killed the engine response and made it feel like it was towing a 2000lb trailer. CAVEAT: The engine was not fully worn in though.
We've never seen it (parasitic loss from oil once hot) on the dyno. As previously stated, even a 10HP gain on the dyno couldn't be detected in the seat.
I don't doubt you, but I have never seen anything like what you are referring too. We have gone from 5/w20 to 15/w50 in an entire fleet of 4.6's (since brand new) to include police and public works vehicles, not to mention dyno tuning a number of 4.6's with and without blowers...never experienced what you describe...????
I'm curious!!!
In fact, 20w/50 was the only oil we used for years in sprint car engines, tow vehicles, wind machines and farm tractors.
When we tuned Frederick Aasbo's event winning Toyota Supra drift car, 20/w50 dino was the oil that he had been using, even during competitive events in Norway...FWIW
The thin crowd on this forum is quite fervent. I remember going from Straight 50 wt on my SBC race car to 20W-50 and thinking how thin it was. Then I switched to 15W-50 M1 and it poured out like water....and worked great in the Suburban too for towing. The BBC Suburban, which no longer tows anything heavy, now has 5W-30 M1 in it and I feel no difference - gas mileage is the same. Maybe the thin is better, I don't know for sure - but if it involves high horsepower or towing, I'd rather err on the side of a little too thick.