[Hikin Mike]

Just this afternoon I took the car out and noticed my oil pressure read 40psi sitting at idle and 60psi driving. Normally its 15-20psi lower on both. Oil level is fine.

Any ideas?

[Bill Hanlon]

Start by putting a cheap mechanical oil gauge into the same port on the engine. Better yet, put a T in the port and attach both gauges at the same time.

[steve25]

Hot oil pressure ( after driving for 15 minutes) should be 18 psi or better at 1000 rpm and 60 psi above 2500 rpm.
I would change your oil filter before running the motor again even before checking you sender!

[HWYSTR455]

Originally Posted by steve25

Hot oil pressure ( after driving for 15 minutes) should be 18 psi or better at 1000 rpm and 60 psi above 2500 rpm.
I would change your oil filter before running the motor again even before checking you sender!

Yeah, that would be my first course of action too, change the filter.

What brand filter are you running?


.

[Bill Hanlon]

I know that the oil pressure port by the distributor is past the filter. Is the oil pressure port on the filter mount between the pump and the filter or on the output of the filter to the block?

[Hikin Mike]

I use Fram filters and I use the port by the distributor. Will change the oil before I do anything else.

FWIW, The car sees maybe 2000 miles a year. The current filter was purchased probably 15 years ago (car was parked for 10 years), so it is an older version of Fram...if that makes a difference.

[Bill Hanlon]

The only way I can think of that would suddenly increasing oil pressure at the distributor is for the filter to clog and the bypass in the filter mount is opening (at about 10 psi difference across the filter). That would account for additional oil pressure in the system.

As many above have already said, change the filter and try again.

As many who are about to post will say, get rid of the Fram filter. Assuming the filter swap fixes the problem, cut the old one open and see what the inside looks like.

After you get it open, use thiss forum's search feature and look for Fram.

[Hikin Mike]

Originally Posted by Bill Hanlon

After you get it open, use thiss forum's search feature and look for Fram.

I'm familiar with the Fram issues. I don't have a filter cutter, so I'm not going that route.

[steve25]

The good news at the end may be that you had a small item of crap from day 1 keeping the pumps check Ball unseated thus lowering the pressure and it has cleared out now!

[Hikin Mike]

Another question.

I've used 20w 50 forever. I used it "because", nothing more. Since I'm going to change the oil, should I change weight?

[dataway]

Yep ... I'd almost guess you don't have a spike in high oil pressure .. you had an extended period of low oil pressure.

[mgarblik]

Originally Posted by Hikin Mike

Another question.

I've used 20w 50 forever. I used it "because", nothing more. Since I'm going to change the oil, should I change weight?

If your goal is to diagnose an oil pressure sudden change issue, I would just change the filter first and see what happens. Don't introduce a bunch of variables into the problem. Changing oil viscosity, and changing from synthetic to mineral based and vice versa will change the oil pressure. I would change the filter, add a quart of the same oil you were using and continue the diagnosis.
Once you are satisfied you have corrected the problem or are happy with what you have, I would change the oil. Personally, 20W-50 is really old school but many people still run it. It really doesn't hurt anything in our old engines, but cost a couple HP and a tiny bit of gas mileage. Driven in cold conditions, 20W-50 can take up to a minute of running time to get any dribbling liquid out of the pushrods. That's a long time to run without any real splash lubrication. 10W-30 has become the general go to in these old muscle car engines unless they are really worn out or have very loose bearing and piston clearances. 10W-30 from 20W-50 will drop your oil pressure about 5 psi hot through the RPM range.

[Hikin Mike]

Originally Posted by mgarblik

If your goal is to diagnose an oil pressure sudden change issue, I would just change the filter first and see what happens. Don't introduce a bunch of variables into the problem. Changing oil viscosity, and changing from synthetic to mineral based and vice versa will change the oil pressure. I would change the filter, add a quart of the same oil you were using and continue the diagnosis.
Once you are satisfied you have corrected the problem or are happy with what you have, I would change the oil. Personally, 20W-50 is really old school but many people still run it. It really doesn't hurt anything in our old engines, but cost a couple HP and a tiny bit of gas mileage. Driven in cold conditions, 20W-50 can take up to a minute of running time to get any dribbling liquid out of the pushrods. That's a long time to run without any real splash lubrication. 10W-30 has become the general go to in these old muscle car engines unless they are really worn out or have very loose bearing and piston clearances. 10W-30 from 20W-50 will drop your oil pressure about 5 psi hot through the RPM range.

Sounds like a plan. Just change the filter. I do have a few quarts of the old 20W-50.

Going to the store now...

[David Jones]

Since nobody asked......

It was fully warmed?

[Hikin Mike]

Originally Posted by David Jones

Since nobody asked......

It was fully warmed?

Yes.

[Hikin Mike]

Just changed the filter (Wix) and that did NOT fix it. Did not change the oil, other than what was in the filter.

[mgarblik]

OK, you now have a good oil filter on it, so that can be eliminated. You didn't say what kind of gauge you have so I am going to assume factory gauge? If it's factory or aftermarket electrical gauge, that is my next suspect. Just for fun, throw a voltmeter on the battery with the engine running and make sure you are not overcharging for some reason. If you are in the high 14+ volt range, the gauge may read high. They have a gauge voltage regulator in some systems but it may not be working correctly. If you are 13.5-14.5 volts move on. Next I would T in a mechanical oil pressure gauge and see where you really are. The mechanical gauge can usually be depended on to give you accurate, actual oil pressure. Go from there. Good luck

[Hikin Mike]

No, it's an Auto Meter and it's about 30 years old.

[Hikin Mike]

To add, I'm currently trying to borrow a gauge. Funds are tight, so I may have to wait until later in the month (Nov) if I need to purchase one.

[78w72]

did it have this issue the last time(s) it was driven? if not, i wouldn't think the oil filter had anything to do with it after just sitting for awhile. but its one less unknown now.

another possibility, since you're running 20/50, did the temp drop any since the last time it was driven? colder temps will make thick oil read higher psi for longer. i see you are in cali, but i know the temps can change quite a bit this time of year depending on location. your weather shows low temps in the mid 30's recently... it could be the engine got very cold & the 20/50 oil was just very thick compared to what you're used to during the summer with lows in the 70's? i live in iowa & right now temps can fluctuate a lot & i notice my oil gauges reading higher/longer than in the warm summer temps. a 2nd gauge is good to check, but if this didn't happen before, it could just be temp & oil related.

unless you're engine is really warn out or built loose like a race engine, i dont think you need 20/50 oil. 10/40 or 10/30 if its keeps good psi is all thats needed for a stock-mild street engine & will have some benefits mentioned above.