Should I run 5w30 oil now. About oil pressure...

[BlackFox5.0]

It's not that cold out anymore, but in the morning when I start my car, my oil pressure is around 85-90psi. Once it warms up And I'm crusing it's at 62psi or so. But when I come to an ilde it drops to around 25psi. Would it be safe, or a bad idea to switch from 10w30 to 5w30? I'm using Castrol SynBlend if that matters at all. I'm just wondering because I dont like seeing my oil pressure peg my 100psi gauge while it's cold.

 

[04sleeper]

You must have a high volume oil pump. Do you have a 7 quart oil pan?
My old GT used to do the same thing but I never ran lighter oil because of it.

 

[CRASH7772]

I was told by a Redline rep that you should run the factory oil weight even with any synthetics.


"In the Mustang I would recommend the 10W30 in the engine, the D4ATF
in the T-5 transmission and 75W90 in the differential.
In the Tremec the MTL can also be used. If the clearance on the rod
and main bearings are remaining stock, the 10W30 would still be a
good choice. The 75W90 would be suitable for the differential or for
a little higher viscosity the 75W140 could be used."

 

[BlackFox5.0]

Yeah I forgot to mention it's high volume. Sometimes I don't like it. Never ran the pan dry though, even though it's the stock pan.

 

[Mustang5L5]

Yeah I forgot to mention it's high volume. Sometimes I don't like it. Never ran the pan dry though, even though it's the stock pan.

That's kinda the reason why your pressure is so high.

 

[HISSIN50]

FWIW, i have had similar pressures on other motors (european stuff) - nearly 100 PSI cold and around 30 hot, and never sweated it.

I would be surprised if the change to 5W-30 knocked your pressure down much anyhow. And i would not want hot pressure at idle dropping any more anyhow, you know.

Just my two cents.

 

[04sleeper]

Yeah I forgot to mention it's high volume. Sometimes I don't like it. Never ran the pan dry though, even though it's the stock pan.

I would be careful with that setup. I have always been told NOT to run a high volume pump with a stock pan due to starving the lower end of the engine.

When I had one on my 88 I had a Canton pan.

 

[SPEED FREAK]

Mine is 90 PSI cold which is pretty normal for a SBF even with the stock replacement oil pump.

 

[HISSIN50]

Mine is 90 PSI cold which is pretty normal for a SBF even with the stock replacement oil pump.

for real? I thought a stock pump limited pressure to around 60 PSI.

 

[Michael Yount]

"Mine is 90 PSI cold which is pretty normal for a SBF even with the stock replacement oil pump."

The relief on most stock pumps is set for 60-65 psi. 90psi at any temp. is not 'normal' for these engines.

I'd give the lighter weight a try. You've got plenty of pressure. See what happens. If that doesn't knock enough off, try 0w-20. Keep an eye on your oil filter - the seal has been known to give way at those pressures; even the case has been known to 'baloon' at 90-100 psi. Next time be sure the internal relief on the oil pump is set to the max pressure you'd like to see.

 

[BlackFox5.0]

That's kinda the reason why your pressure is so high.

I was just wondering if thinner oil would stop my 100psi cold oil pressure.

I never had any problems with any seals blowing out because of the high pressure.

 

[Stang8URMPRT]

In my 83, I had a HV oil pump and the stock pan. never ever had problems with it... I also ran 85-95 psi of oil pressure at RPM when it was cold, but when hot at RPM it would run about 70 psi... at idle hot it would be around 50ish. I always ran 20W50 VR1 racing oil. I switched to Mobil 1 5W30, and the oil pressure DROPPED when hot to about 50ish cruising, and 15-20 at idle. Fug that... I put my 20W50 right back in, and it was back to normal. Never did I have gasket blow out on the filter or have a filter ballon. Don't worry about it man. You will be fine, and stick with what you have now.