How's my oil pressure?

[karrboy77]

First off I have a 98 GST, I bought it and drove it for a wile before changing the dirty oil in it...I know that should have been the first thing I did. Anyways I was always running 70-75 psi for my oil pressure, now i got it changed with Mobil1 and ever since if Im crusing at say 60 in 5'th im only at 50-55 psi now. The pressure climbs fine at higher revs but its considerably lower at slower speeds now. Is this normal? Could it be the better clean oil or the weight, or do I have a problem?

 

[andymoraitis]

A thinner oil will of course lower oil pressure as will the use of a synthetic (slightly thinner than mineral oil). What oil did you use for the oil change and what grade?

More info would help,

Andy

 

[karrboy77]

Thanks for getting back to me....it was Mobile1 5w30

 

[PieEyedPiper]

I'm pretty sure it says right on my car to use 10w30.
What does your car say?

 

[andymoraitis]

5W-30 is pretty thin stuff. I wouldn't recommend anything less than a 10W-30 in a turbocharged car and I can't even say that I'd recommend that wholeheartedly. Our motors make tons of heat and nothing protects parts better than a thicker synthetic or mineral oil.

Following my rebuild, the machine shop AND my mechanic (Mistu 3 Diamond ASE Master) both recommended 15W-50 synthetic or 20W-50 conventional. Try a thicker oil and see what you get.

Also, if you're using an Autometer oil pressure gauge, the sender may be going south since they can't take the vibration. Mine was giving me low pressure readings and changing it out brought them back into normal range (25 psi hot idle, 100 psi at WOT).

 

[karrboy77]

well I just took it to a place to get it changed and thats what they put in , would you recomend changing it now to a thicker weight or will it be fine for now?

 

[andymoraitis]

If you can afford to change it, I would. Oil is cheap insurance while 5W-30 isn't going to kill anything I prefer the thicker stuff.

It's really your call,

Andy

 

[karrboy77]

Thanks for the help man.

 

[andymoraitis]

Thanks for the help man.

Anytime! Let us know the difference in going with a thicker oil.

 

[jltcat]

suggest running 20-50 synthetic for hot climates (80-100+ climate).. dont use in cold winter climates use 10-30 or 10-40 during really cold times (20 degrees and below climates)