V10 Motor Oil
All, Well, I've done it now. I brought home a new class A. Mine is on the FORD F53 chassis. The oil fill cap & owners manual state it is to use 5W20 motor oil ? WOW! That sure is thin....
Forum Discussion
conceptumator wrote:
Maybe this will clarify. I asked the same question on the V10 to my mechanic and race car friend and his explanation makes a lot of sense. The oil type is determined based on the manufacturing tolerances in each engine. As tolerances get smaller, the oil needs a different viscosity. Using any weight other than recommended is a gamble.
Sigh.
Again, tolerances and clearances are two different things. The MINIMUM clearance of a bearing doesn't change with reduced tolerances. It stays the SAME. On the other hand, if machining tolerances are cut in half, the MAXIMUM CLEARANCE of a bearing in a production engine will be cut in half-----BUT THE MINIMUM CLEARANCE WILL STAY THE SAME.
The reduction of the MAXIMUM CLEARANCE allows the engineers (and CAFE managers) to use a thinner oil at operating temps-------which slightly helps mpg.
The viscosity of a 5w-anything oil will all be similar at startup-------and 100 to 1000 times thicker than at operating temp. That is a 5w-50 oil will be much, much thinner at operating temp than a 5w-20 oil is at startup-------and they both will be a similar thickness (viscosity) at startup. If the bearings don't seize at startup with a 5w-20 oil, they won't seize (or wear), at either startup or at operating temps, with a 5w-40 oil.
