ok this is odd when i crank my truck the oil pressure gauge says there is no pressure. When i give it gas and rev it to about 1000 rpms the pressure comes up to normal till i let off and it goes back to nothing. My mechanic says its either the low pressure oil pump or the main bearing. Anyone that has any input on this would be great before i go puttin money into this thing. oil pump and housing everything installed aint but about 500 bucks so not to bad but i dont wanna have to put that into it if i dont have to.

Awesome site by the way

 

how many miles are on your truck? I think it could be either one, main bearings are fairly inexpensive but are probably more expensive to install bcuz to remove the oil pan you have to take out the engine. I had the same problem with my old 68 big block ford highboy but i think it was mainbearings. depending on how hard the lp oil pump is to install I might try that first

 

Try a new sending unit.

 

i replaced the oil pressure switch and still same thing. The truck has 300k miles on it and it runs like a top, like it idles fine run down the road fine no hickups or anything.

 

15w50?