I have low oil pressure once my 88 Trans Am GTA 5.7 350 TPI warms up, I have the oil pressure gauge when I start it its at 35 then once its at warm regular Temp the gauge drops to the red which has been doing that for the past year with no change in engine performance!!!! I just always thought it was the Oil Pressure Sensor/Swith but i changed it with a new sensor this weekend and now the oil pressure gauge is reading higher at start up but once it runs to warm reg temp it drops to the red zone again!!!!!!!!! If I have been driving in the red zone for over a year with reg oil changes and no change in engine performance or knocking could the gauge be broken??? Wouldnt the engine have seized up with no oil pressure with reg driving for over a year????? I use 10W-30 Mobil 1 Oil with Mobil 1 Oil Filter. Been hearing good things bout Royal Purple has anybody tried it??? Need new oil pump??? Or a complete overhaul of the engine which will suck???

 

Your thread title states 5W-30 but the text of your message states 10W-30. Personally, I wouldn't use 5W-anything in any vehicle I have. Mobil 1 10W-30 at a minimum, and that has worked fine for me from -43ºF to over 100ºF. In summer I use 15W-50 Mobil 1 in several cars. If you study the actual SSU viscosity of synthetics both cold and hot, you'll see why 10W-30 synthetic flows better cold than 5W-whatever mineral oil, and even many 0W-whatever oils.

As for your problem at hand, excess clearance is likey an issue. If you can establish an actual pressure with a mechanical gauge and veryify your readings, consider a new set of main and rod berarings, and a new oil pump with good volume and a proper relief valve.

 

Yup, get a real gauge on it. If it's still low, time for an overhaul.

 

happened to me, i drove around for 3 months with my gauge steady in the red, Replaced the sensor and it was still the same. My engine siezed and spun a bearing shortly after. Rip of a valve cover, if you have alot of sludge thats the problem and its time for a rebuild.

 

Yea thats a clear indication your bearings are shot. If you want to stretch it, try some HEAVY oil. Like 20w+