94 Chevy with a 350 tbi engine low oil pressure??

i carry 40 psi at idle or park will stay that way for hours until i drive it. then go down to 30 psi until you go to stop then it drops to 10 psi. lower end of engine completely rebuilt. New bearings, oil pump,tube,manual gauge added..torqued to right specs.. and this is the 2nd engine i put in my truck thats doing this... had 4 mechanics look at it and no one can tell me what is the problem.

any other ideas or if anyone else had/has this problema nd fixed please tell me what it can be.

Update:

im a girl also xD oil sending unit was replaced.. this is 2 engines doing this one brand new in the same truck. i will try using a heavier oil the compression honey stuff helped it hold some pressure but im scared this engine is failing on me and i dont see how.

3 Answers

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  • 6 years ago
    Favorite Answer

    Check the oil pressure sending unit... But I am a girl so... But I had a ford ranger brand new and it did the same thing. Issue was... The viscosity of the oil was too thick in 40 below Minnesota winter so it did the opposite it would be low with warning lights until the truck warmed then the guage would shoot straight up! But they replaced the sending unit twice to rememdy the situation . also excessive bearing clearances can cause situation if it was rebuilt....was this always an issue...its obviously an issue with something you didn't change out ... Good luck

  • 6 years ago

    use 5-40 0-40 oil, (5-20 or 5-30 is too thin), the other answer was obviously using the wrong grade of oil

  • 6 years ago

    Use a heavier oil. If you are running 10w/40, change the oil and filter and use 20w/50

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