Re: oil pressure drop, but oil level fine...

[Audial@aol.com]

It isn't surprising that you're seeing lower idle oil pressures switching
over to 5w40 synthetic oil.  5w40 refers to the fact that the oil flows like
a (very light weight) 5w oil at low temperatures and like a 40w oil at high
temperatures.  Oil pressure is caused in part by the viscosity (resistance to
flow) of the oil you are using.  Most Audi's call for a 10w -- oil in the
owner's manual and you are using a lighter lubricant.  

As long as your oil pump is providing enough oil _volume_ to maintain
sufficient hydrodynamic lubrication of all of the bearing surfaces in your
engine, the pressure drop at idle shouldn't concern you (as long as it's not
in the region of 0).  Since you have been driving your car, and it hasn't
seized or otherwise self-destructed, your oil pump is probably OK.  In the
meantime, you are enjoying the slight horsepower benefit of the lower pumping
losses associated with using a lighter weight oil...Chevrolet engineers did
the same thing when they switched to lower-viscosity lubricants on newer
Corvettes.  I'd just fix the leaks.

Best Wishes,

Alex
'86 5KCSTQ