[T2] Oil weight

[Jamie]

----- Original Message ----- 
From: "Jim Denton"

> The VW oil cooling system is designed to allow the oil to get hotter and
> hotter until the viscosity is lowered to where the engine wants it.

so,, multi weight oil.. cold engine,, thick oil,  pump builds pressure,, oil 
cooler bypass valve opens.. excess pressure relieved by putting oil back to 
sump to be reused,,, this reuse cycle allows the oil to heat up faster.. 
thinning the oil.. lowering the back pressure ,, allowing the relief valve 
to stay closed longer.. and the oil to pass thru the cooler.

when does the oil pressure going under the set pressure of the switch, 
become OK?
when the oil lamp flickers, the pressure is below the set pressure of the 
switch..

i've always been one to have a "loose" engine,, not factory TIGHT 
tolorances... which requires more volume of oil to keep up the pressure 
required to keep the crank spinning on a film of oil ,, not grabbing the 
bearing shell and causing wear.
so even tho I start out with "worn out" tolerances between the crank and the 
bearing.. the higher volume ensures there is VERY little wear on the 
bearings in 60k miles +.. because the oil pressure / volume remains high 
enough to float the crank.

I guess what I don't know, is what pressure is low enough for longevity.. 
for that matter I don't know what high pressure is too high..

this chart says to me... any oil you use will become almost virtually the 
same viscosity as soon as it gets hot..
http://www.ratwell.com/technical/OilSelection/OilViscosityChart-Valvoline.gif

Ratwell has a pretty intense page to go with that ...  and I think it all 
boils down to not worrying about viscoity if you have correct oil pressure 
by having enough volume .. but to ensure their is enough ZINC to keep the 
camshaft and lifters mating surface lubed..........

keeping the bearings lubbed isn't high priority any more..

http://www.ratwell.com/technical/OilSelection.html