I have a 95 F-150, with 154k. I'm the original owner, and for most of the life of the truck the oil pressure needle was always at the "A" in normal.

Over the past few months, when the truck is first started and until I drive for 5 minutes or so, the needle indicates a lower pressure at "R".

Change the oil and filter did not make any difference.

Is this an indication of something wearing out/clogged? Overall, the truck is running fine. The oil pump is original.

 

Since the gauge really isn't a gauge, don't be alarmed. The gauge is in fact an oil light the way it is set up. In the beginning of the forum section there is a discription of a method by removing a resistor and changing the sending unit to make it work as the electric gauges used to. You really don't have a problem as the gauge reaches somewhere in the center of its travel at 6psi. .

 

Or just get a Sun oil pressure gauge and install it. Then you'll have the actual PSI numbers. Look at my gauge in my gallery.

 

Being rather new to the I-6 fan club, could you clarify your oil pressure statement for me: Are you saying that the 300 I-6 is "G2G" at 6lbs oil pressure, and would read average on a properly working stock guage? One mechanic (who sold me the truck) some time ago told me that 7lbs was OK, but frankly I thought he was full of ... something. (didn't really care, just wanted the truck). My 89 starts up at (new mechanical guage fed by oil tube from the sending unit hole) around 50lbs, settles down warm to 25-30 at 1500 rpm, and idles at 750rpm at about 12 or so. And frankly I've been concerned that it was way too low, probably needed a bottom end job or new oil pump. I saw the engine out of the truck, (upside down on an engine hoist) before I bought it and he said he had rebuilt the engine (lots of room there for definition of rebuilt, this was in a Ford dealership rapair bay). All cylinders hit 175psi (+-2psi) so the upper end is good. I've just been concerned about the bottom end due to what I considered low oil pressure. So if you're saying that 6psi would read average on a working stock guage, then I'll have to rethink my low opinion of his definition of what's OK as well as his definition of overhaul.

'89 F150 I-6 4WD 5spd SWB

 

I go back to the same statement I made on another forum on oil pressure, 10 psi per thosuand revolutions per minute is an accepted standard, no need to concern your self unless lower then that. I often think back to the old Chevy 215 6 and the one Hudson engine both of which ran at 15 psi max, and they ran a long time. The chevy had a tube in the pan with six noozels aimed at the dippers on the rods and squirted oil into those babbit bearings. My buddy and I each owned one and we ran the life out of them no problem oil wise until a slipping clutch at high speed (70 mph) left my buddy run his at full throttle and away went a rod bearing. Just my 2 cents.

Kotzy

 

OK, Kotzy, thanks for the insight. Guess I'll quit wondering about the oil pressure, as it's above 10psi/1,000rpm for sure. Still don't understand why it would start out at 50psi and then drop to 25/30 going down the road at 55 or so, and then drop to 12 or so (in between marks on dial) at idle. Seems that when the variable density oil is cold it should be thinner, and then when it heats up it should be thicker...
But your post has made me a lot more comfortable, this is my desert-dawg with it's 4wd, low gears, low-rpm torque, granny-crawl-speed on rough trails, short wheel base, sharp turning radius, high clearance for ditch banks and all, ... I was concerned that the bearings were worn despite being laid out on the bench at the Ford Garage...
Thanks again. ;-)

 

Your oil will be a lot thicker cold. Variable density oil (you mean multigrade?) just means that, for example take a 10w30, when cold it will be like a 10W and when hot it will be like a 30 weight. If you had straight 30 oil it would be a lot thicker cold than a 10w30, but either one is thicker cold than hot.

I assume you have a 4.9L I6. Spec oil pressure is 40-60 psi fully hot at 2000 rpm. 50 psi cold is fine. It should be lower hot and lower yet at idle. See what you get at 2000 rpm. If you have 25/30 at 1500 rpm, might get 5 more psi at 2000.

All in all, your pressure seems a tad on the low side, but follows the 10psi/1000 rpm rule.

I had hot pressure of 35 at 2000 with idle around 16 on 10w30, so I switched to 10w40 and get about 44 at 2000 and idle around 20. You could run 10w40, though probably not absolutely necessary. I just like being in the spec range. I wouldn't go much thicker than that though. If you live where it gets cold in winter, can go 10w40 summer and 10w30 winter. I plan to run 10w30 next winter.