Originally Posted by Fordtrucks (Post 4221891)

I would wonder if I should run tighter Clarence's in a motor that I'm building that will be all forged lower end, have a ProCharger at 8-10psi and never break a water temp of 100°F then say a similar motor that warms up to 200° and stays there. My motor running so cold may not expand as much.. For cooling the bearings, I like the idea of a little lost with a heavier oil "VR1,20-50" and a bigger oil pump.. As for load/vers oil viscosity, I'm not sure.. My cat engines in my OTR semi trucks have a high load, slow rpm deal and run 60-80 psi oil press with 15-40 but the otr Cummins isx engine maybe make 30 psi hot. My new Volvo runs 10-30 summer, 0-30 winter. Not quite a boat motor tho.

Originally Posted by COOPS (Post 4219697)

5 quart capacity that has an allowable usage of 1 quart every 600 miles. This same motor has a recommended change interval of 10,000 miles.... Do the math. Less than half way through your oil change you could be replacing your engine instead of the oil. 0w-20 is like antifreeze consistency.

Originally Posted by SB (Post 4219657)

Yes.

Many cars that come in here have oil caps that state 0W-20. Some 5W-20, etc, etc, you get the drift.

So two things, not only thinner oil but only synthetics found in that weight category.

.

Originally Posted by Black Baja (Post 4219679)

In 2009 the federal government mandated auto manufacturers recommend 20wt oil. If the manufacturer did not comply they had to pay a fine for that model. Not all manufacturers have complied with every model. What I have noticed when the switch to 20 wt was made. Oil consumption is very high most cars are running out of oil before there normal change interval. I work on a ton of cars. Probably 30-50 different makes and models a week. This is what I have witnessed as a trend with 20wt oils. You can have them.

Originally Posted by MILD THUNDER (Post 4222223)

I find it interesting that in the new vettes, GM recommends 5w30 for normal driving, but states for high performance driving or racing, 15w50 is to be used.

Id consider when my boat engines are at 4000-5700 rpm out on the lake, thats high performance operation. My stuffs quite a bit looser and making quite a bit more power than a new vette engine.

Originally Posted by minxguy (Post 4222219)

Not sure about the government mandate for 20 weight, but let me throw this out for discussion. Do you think that there might be a corolation between the mandated amount of zinc in oil, running a lower viscosity, and lower oil ring tension all having an effect on catalyic converter life?

Lets face it, we had cats in the past and we were running higher zinc oils that were of a higer viscosity and much lower oil consumption

Is the lowed zinc levels really a result of energy conserving measures (lower oil viscosity/less ring tension) applied by the OEM's to help meet federally mandated CAFE requirements which in turn cause more oil consumption which in fact poisions the cat?

Ken