Low Oil Pressure 1993 Ranger 4.0 140k miles

[Angry Possum]

My oil pressure is running on the lower side of the needle gauge, its a little above the 1/4 mark on the gauge. I had changed the oil about 1k miles ago, I used 10w-40. My engine has about 142k miles. Is this normal to run a little lower on the oil pressure? Anything to be alarmed by it. I live in the East coast where it's cold, could the lower temps outside cause lower oil pressure.

 

[Blmpkn]

That guage is a dummy guage.. as long as its not pegged on 0 your pressure is just fine.

What made you pick 10-40? That motor doesn't call for 5-30 or 10-30?

 

[Angry Possum]

That guage is a dummy guage.. as long as its not pegged on 0 your pressure is just fine.

What made you pick 10-40? That motor doesn't call for 5-30 or 10-30?

I've been using it in the hotter months. They say thicker oil is better for older engines with mileage especially in summer. However Im not sure that it's true. Your thoughts...

 

[Angry Possum]

I may dump some Marvel Mystery Oil in it to thin it out perhaps. Is that a good idea?

 

[Angry Possum]

PS I don't have any valve ticking, seems to be running fine

 

[rusty ol ranger]

PS I don't have any valve ticking, seems to be running fine

Gauge issue.

Check the connection at the sending unit...make sure its clean and tight. If that dont work change the sender.

It only takes 3psi for the gauge to read "normal"...so it either will sit 100% normal or show zero. Anything else is eletrical or sensor related

 

[Lefty]

I would add some Seafoam according to the directions, drive it around for the recommended time, then change the oil again returning to the recommended weight. Perhaps also use all synthetic oil. You might even do the same on the next scheduled oil change.

 

[Shran]

My rules of thumb with oil pressure - a healthy engine should make about 10psi per 1000RPM, and if it's not making valve train noise, it's got at least some oil pressure.

Gauges in these trucks are funny. People wanted gauges to watch what's going on in their engines, so car makers added gauges, but people don't like to see any movement in them, which would be totally normal. Car makers then replaced gauges that were instantly accurate with ones that were not much more than a dummy light and people freak out that there's not enough movement. So we are stuck with what we have now... cars with a gas gauge and a speedometer and nothing else.

My wife's Prius just has a big angry triangle light that comes on if there is some problem. Could be low oil, no oil, overheating, who knows?

 

[sgtsandman]

I would add some Seafoam according to the directions, drive it around for the recommended time, then change the oil again returning to the recommended weight. Perhaps also use all synthetic oil. You might even do the same on the next scheduled oil change.

Either or both will clean out the internals.

One caution though. Engines that have lived their life with conventional oil have been known to spring all kinds of oil leaks when switching to synthetic. There are two reasons for that. One is that the ability to swell seals and gaskets is different and they may shrink as a result. Two, existing leaks that got gummed up with varnish and deposits get cleaned out by the synthetic and thus are no longer sealed and holding oil. So, switching to synthetic, while better for the engine long term may cause a lot of work and frustration in the short term.

For an older engine, it may be better to just stick with a quality conventional oil. Where that cut off is, I couldn't tell you. Some of it will depend on the engine in question and some of it just because of mileage and old age. Doing the switch to a relatively new engine is almost never a problem. I have never heard of one having a problem with a newer engine but I can't say it has never happened either.

 

[rusty ol ranger]

My rules of thumb with oil pressure - a healthy engine should make about 10psi per 1000RPM, and if it's not making valve train noise, it's got at least some oil pressure.

Gauges in these trucks are funny. People wanted gauges to watch what's going on in their engines, so car makers added gauges, but people don't like to see any movement in them, which would be totally normal. Car makers then replaced gauges that were instantly accurate with ones that were not much more than a dummy light and people freak out that there's not enough movement. So we are stuck with what we have now... cars with a gas gauge and a speedometer and nothing else.

My wife's Prius just has a big angry triangle light that comes on if there is some problem. Could be low oil, no oil, overheating, who knows?

Ford switched their trucks in the late 80's and supposdly their was a TSB saying "if customer comes in complaining of oil pressure gauge movement replace sending unit with updated version #######" or something similar.

So instead of a service manager explaining why your new broncos oil gauge drops off at idle and comes up with RPM they just said they "fixed" it

 

[Blmpkn]

I havnt held a jug of MMO in a bit.. but I seem to remember the stuff being MUCH thicker than a 40wt oil. Dumping it and filling it with whatever the manual calls for would probably be best. I personally wouldn't consider a 93 motor "older" or 140k "higher mileage" so regular weight oil would probably be just fine.

 

[franklin2]

I may dump some Marvel Mystery Oil in it to thin it out perhaps. Is that a good idea?

Please do not spend any time or money on what the stupid factory oil gauge says. If you want to spend some money, a set of aftermarket gauges hanging under the dash is a good investment.

 

[Angry Possum]

This is the reading. I'm gonna check the oil in a few. Last time I checked it was full about a week ago... You never now.

 

[Angry Possum]

Just checked, It's a quart low. I'll put some in, and see if the gauge reading changes.

 

[bobbywalter]

Please do not spend any time or money on what the stupid factory oil gauge says. If you want to spend some money, a set of aftermarket gauges hanging under the dash is a good investment.

Or just buy a gauge to test with. Often ground issues will throw off the dash...when in doubt test with a good gauge.