A lighter oil will flow easier, but it won't result in higher oil pressure. If anything the oil pressure will be lower. The oil pressure is higher on a cold engine because the oil is thicker at low temperarture. Oil getting dark is an indication that the detergents are doing their job and cleaning the engine. An oil that looks clean all the time, is not doing a good job of keeping the engine clean.

 

ok i have a 97 camaro ss and right now i have 10-30 mobil 1 full synthetic oil. when the engine is FULLY warmed while in gear (i have an automatic) its like idk 11 12 13 sumwhere around there. but when im at 5000 rpm im not at 55 psi im prolly more around 45 psi. does this mean anything? the motor runs great so idk im just makin sure that thats alright. another thing to note is. when i check it at the 5000 rpm im either in park or neutral so maybe its because its not in gear and not as much load on it. idk let me know what u think

 

most likely the stock instrument clusters arent 100% accurate, i would get a aftermarket oil pressure gauge,and i know everyone is concerned what the lowest psi should be, but what is the highest psi could be ?

 

The highest PSI is set by the relief valve; however, if the oil is too thick the pressure will exceed the relief valve setting. Unless you have an all out racing engine, pressures over 100 PSI could cause problems, ranging from broken pump drives to eroded main bearings & stuff in between such as blown filters, blown seals, etc...