Originally Posted By: Titan
Originally Posted By: blueiedgod
Originally Posted By: 06VtecV6
I can tell it revs higher not due some butt dyno but looking at the RPMs and seeing that with full syn, the car revs at around 2500 RPMs at the same speed(around 80 mph) and with syn blends, it revs at 2000-2100 rpms and the power felt the same as in it would rev faster with the lower rpm and rev slower at the higher RPM with full syns.
I am not completley knocking down your theory, but if your engine revs at different RPM's at the same speed before and after an oil change, I would check the transmission. Unless you have a CVT tranny (which by the vehicle in your signature, you don't) You are looking at a slipping tranny. The gear ratios are fixed and do not adjust based on the engine output. If you are cruising in 5th OD at 2500 RPM before the oil change and at 2000 RPM after the oil change at the same speed, your tranny is toast.
Well, if you won't completely knock his theory, I will. That theory is 100% wrong. The rpm of a cruising engine with an engaged torque-converter will be EXACTLY the same at a given speed, no matter if you had no oil in the sump or 140 weight gear oil. IF there was a difference in rpm at a given speed in this car, it was because in one case the torque coverter was "engaged", and in the other case it wasn't engaged. This has NOTHING to do with engine oil viscosity. Sheesh!
Well, I didn't want to be categorical, since I have no experience with automatic transmissions. I know with a manual, the change in engine RPM at a given speed indicates slipping clutch.
Automatics... who cares, they are for girls anyway.