guess i don't know how to use the search on this website properly, seems like it's been talked about before but can't find it.

My 87 will start up fine with a jump and has normal oil pressure, after running a few minutes it'll slowly drop by only a few psi. then after reaching operating temp i guess, the pressure just drops alot and i have to cut the engine. sooo
can i put 10w30 in it for now and see if that helps?

 

What oil are you using now?

"Start up fine with a jump"?

First step in diagnosing an oil pressure issue is to install a mechanical oil pressure gauge (either temporarily or permanently). Verify what your oil pressure actually is. A good bit of the time the problem is the oil pressure sending unit and not the oil pressure itself.

 

If car is running normal and no strange noises (i.e. pinging, knocking) then 90% of the time it is the oil pressure sending unit.

 

Good to know, my gauge reads zero most of the time. I get maybe 10 psi around 3500-4000 rpms. It runs perfectly fine, as in it doesn't sound like its starved for oil, it has pretty of other problems.

How hard is it to replace the oil sending unit on a small block?

 

My L98 has it just above the oil filter but I've heard it can also be close to the firewall on other engines. Sending units range from $15 to $80 and take 5 minutes to install.

 

The older style is close to the firewall. IIRC, it's cylinder shaped with a tab and it's screwed into like a t-shaped guy or something like that. The newer one is by the filter, but it can be a pain to get your hands around it.