Alright,
Here's the situation - I have 125K miles, engine's in great shape, never had a oil pressure problem before now. I use Amsoil and a Nissan oil filter. I ended up having to pull the lower and upper oil pans to replace the dust seal under the rear main (I couldn't get that sucker to go in any other way).
Used to be - the oil pressure light would cut off immediately at startup. Now it takes a 2-4 seconds, unless I turn the car off and crank it back up right away (then it goes out immediately). I replaced the sending unit already and no difference (though I figured that wasn't it). The filter is still holding oil up in the engine, so I don't think it's a problem with the filter.
So, what do you guys think I screwed up?
I figure it could be 2 things, but if anyone has any other ideas I'm open to them.
1)The O-rings that go between the upper oil pan and the block
2)The oil pump pickup tube seal (I really hope it's this one).

 

The oil seal area needs to be sparkling clean. Lacquer thinner works fantastic.
other then that, the pickup tube gasket is hard to mess up.

5w30?

 

Willing to bet it's the two o-rings for the oil pump should have been replaced when you dropped the upper.

 

He probably did I hope!


the OE ring is flat and doesn't really fit in there snug.
The new part is round, and fits nice and tight.

Reusing that old one looks like it's pain.
90% sure you'll mess it up because it won't stay in place.

They were 4bux! the pickup tube was 2bux. No way anyone would cheap out on that stuff