Oil Pressure with M1HM 10w30

Status
Not open for further replies.
Joined
Sep 21, 2011
Messages
484
Location
IL
1994 F150 4x4, 302 engine, 217k miles. FL1A, M1HM.
I've owned about two years, but was one-owner and well maintained with records of regular oil changes at Ford dealership. Leaks at rear main, probably burns some, but no noticeable signs of it. Every time it is driven (about 10,000 miles/year) it pulls about 3,000 pound total weight in mower and trailer.
The oil pressure has become progressively worse. I assume it's not the sender as every Chevy I've had showed oil pressure gauge irradically (quickly) jumping all over the place when sender gauge went bad. This is nice and steady and spends a good deal of time just below the "normal" word, but a long ways from the truly normal mid-point.
I moved up from 5w last year, but don't really see much difference. Pressure seems to show better for the first 200 miles after an oil change (maybe coincidence) and after for an entire trip after it has really been opened up (turning overdrive off and accelerating to pull trailer up hill (not alway, so may be a coincidence too)
I surely don't need thicker than the M1HM10w30...could this actually be the gauge, or am I running it oil-starved?
 
I had a similar issue, and it was caused by an oil leak. The leak from my push rod cover coated the ground wire for the oil sending unit with oil where the ground connects to the engine block. When I replaced the gasket and cleaned up the area the pressure went back up to the normal range again.

I'm not saying that's your issue but having a look won't hurt, and verifying oil pressure with a mechanical gauge is the only way to get a real reading.
 
Pretty sure a 1994 Ford is going to have a fake oil pressure gauge. It just always shows normal, unless it's below a set minimum, then it will show low.
 
You've got an issue with your gauge cluster. If it is wandering around or reading anything other than the middle, its in the cluster.

The oil pressure switch is on or off, then the cluster filters that signal through a resistor to make the gauge read in the middle of the range. So long as you have more than 7psi, it will read in the middle. It's a ford thing.

Spend a few minutes and install a mechanical oil pressure gauge to see what your engine is really doing.
 
Originally Posted By: Miller88
Pretty sure a 1994 Ford is going to have a fake oil pressure gauge. It just always shows normal, unless it's below a set minimum, then it will show low.
This.

Originally Posted By: meborder
The oil pressure switch is on or off, then the cluster filters that signal through a resistor to make the gauge read in the middle of the range. So long as you have more than 7psi, it will read in the middle. It's a ford thing.
And this.

My old 1990 E350 work van and my 2000 MGM and 2003 Marauder all have (or HAD, in the case of the Marauder) fake gauges, so likely your 1994 does, too.
 
OTC-Tools-5610.jpg
 
The M1 HM is A3 HTHS >3.5cP. If the gage is correct you could substitute some M1 10w40 1 or 2 quarts to push the HTHS to 3.7cP

You may want to get after that seal, though. If y our gonna keep the vehicle other than a yard or farm truck.
 
Last edited:
That's a dummy cluster/gauge as others have stated. Easy to confirm though:

Drivers-side of the motor, right in front of the oil filter, that is where the oil pressure sender is. if it is a big honkin' thing that looks like this:

large.JPG


It is a real gauge. If it is this tiny thing (or similar):
Oil_Pressure_Sensor_For_FORD_HOLDEN_E9SC.jpg


It is just a switch, which means what you are seeing is electrical related, and has nothing to do with the oil pressure in the engine.
 
Status
Not open for further replies.
Back
Top