Motor oil

[beardedman10]

So I have an 1993 GMC sierra. I run 15w40 and im curious if i could/should put lucas oil stabilizer to help with oil pressure. After the motor get to operating temp the pressure goes down when idling. I know i need a new motor in the near future but cant afford it. Just curious if anyone has info.

[txab]

What are your pressures? Have you double checked with a mechanical gauge?

[richard wysong]

I had the same problem with my 98 after a bad rebuild where they didn't mike the crank so it has low op when hot idle. I run Castrol conventional 20w-50 and the pressure stays around 30 at hot idle. I tried Walmart oil and it quickly loses viscosity when the castrol doesn't for about 2000 miles. I got into a big argument on the Cadillac forum over this, they all swear Walmart oil is the same as name brand but my experience proves them wrong

[richard wysong]

 I don't think Lucas will help with the op but it does stick to the metal and adds onother layer of protection to the bearings

[CamGTP]

The engine only needs like 5-7psi to idle without damage, if it's above that you are just fine.