Originally Posted By: Geonerd
Here's our good friend, the Stribeck Curve.
It plots wear and oil film thickness as a function of RPM, load, and oil viscosity (HTHS).
Let's assume your stock engine, running xW-20 oil, was operating somewhere around 40~50 (on the horizontal axis) when under maximum stress.
You've gone and nearly doubled torque. This should have a similar effect on bearing load. Suddenly, you're operating in the 20~30 zone, and the oil is starting to give way. To make things worse, the supercharger will be produing max torque at relatively low RPM. Since high RPM helps maintain oil film, his further divides the formula's number, moving you further to the left.
Now, there are anti wear additives in the oil (like ZDDP, Moly, etc.) that allow hardened steel surfaces (like those found in cam gear) to survive continued operation in the mixed/boundary zone. I don't know how effective these additives will be when plain bearings suffer oil film collapse. Plain bearings not built of steel and are not (IMO) really designed to survive much rubbing together.
Since we don't know how much safety margin your car had to begin with (how far to the right of the ~35 danger zone), we don't know exactly how much thicker an oil you should run.
Without a better understanding of specifics, I'd suggest you double the HTHS of the oil you run. This gets you into the xW-40w/50w zone, with HTHS values near 5. M1's thickest is 15w-50, close at 4.5. Redline's 10W-40 measures 4.8, and I might be tempted to toss in a quart of something even thicker.
Over time, with UOA analysis to guide you, you could probably work your way down to a thinner mix. This would recover a few of the HP that the thick oil will rob your engine. But for now I'd be inclined to be safe.
Go find some syrup for your car!
HaHa!!
I'm looking at the Redline 40 weight now.. I'm not worried about the few hp the oil will eat. ..the VCT functionality is worry'n me now though.
