well after i fixed everything on my car about the oil pressure. While cruising around town around 40-55 mph the oil pressure sits at around 35 psi in OD, but if i drop it in drive it goes up to about 45.

Idle is 20 and wot is 70. Now im thinking the oil filter (ac delco) could be a cause of a little bit low oil pressure at cruising along with 10-40w penzoil.

Now my next change will be mobile 1 synthetic, prob 5-30 or 10-30 with a witz 1qrt oil filter.

Now u think this would make the pressure come up some or actually make it drop even lower?

 

anyone?

 

You oil pressure values sound right to me; what values are you expecting?

 

40-50 at cruising!

 

A "rule of thumb" posted here often is 10# of oil pressure for every 1,000 rpm; so most people cruise at about 2,000 rpm = 20# of oil pressure.

 

The oil pump is effectively a "positive displacement" pump. The volume of oil it pumps is directly proportional to the RPM of the engine. It is completely normal that the oil pressure will drop when you shift it into overdrive. There is nothing wrong with what you are seeing.

 

k good.