Originally Posted by alarmguy
I have agreed for a long time on the bearing thing but here is why, just found this, "Too thick oil, wonderful oil pressure, yet parts inside the engine could actually be starved for oil due to lowered volume. Another downer, circulating oil accounts for nearly 50% of engine cooling, so reduced oil-flow reduces cooling causing lubricated parts to operate at higher temperatures. Higher parts temperatures, more wear."
I am not concerned with "oil starvation"; modern engines have positive displacement pumps and the oil pressure remained the same for both oils (about 31 PSI at highway speeds). At 210-225°F oil temperatures, I would have to believe the oil is "thin enough" to reach all of the critical places.