Rob D

this problem happens at start up but I have also noticed it when the car is in park or when their is no laod on the engine. It only seems to happen when you rev the engine to 1500 rpm's. Oil pressure is okay. Car is a 1993 Pontiac Grand Prix with a 3.1L LHO V6 it has 158,638 miles and I use 10w30 castrol oil and fram ultra filters
I have tried lucas oil and thats why my engine has this knock.
The engine will knock only in the morning for maybe 3-4 seconds then it goes away and it will not knock on a hot reastart. If I rev the engine it will not knock. There is no metal shavings in the oil or inside the oil filter.

Dbl Monday

Re-build or re-place..in either case, start using Amsoil. Put in the engine,tranny,diff. what ever needs lubrication..

Once it starts to knock, it's only a matter of time..

Legacy

You know, there is an oil additive from Lucas, which makes some real good products. This product is so good that it might just do the trick. Try it out. It's less than $10.00. Worst case scenario is that you added a great additive to your engine that actually helps it out and will just help lubricate your engine and if you actually add one to every oil change, you can even prolong the life of your engine. If that doesn't work you'll most likely have to replce it which can get costly. you can get it at any convenient auto parts store like Advance Auto Parts or Auto Zone.

eric.s

I assume that you don't want to dismantle the engine and fix it correctly?

Try a thicker oil, or oil additive. The prior post mentioned an apparent British product. I haven't looked lately, but STP Oil Treatment used to be around in the US and was a thickener.

This solution might cause new long-term damage elsewhere, since you would be deviating from the manufacturer's specification, and areas of the engine would probably not receive fully adequate lubrication, leading to eventual excess wear.