Low Oil Pressure

I am the proud owner of a 1990 Subaru legacy. The car has had minimal repairs, and currently has over 300,000 miles.
My oil light comes on, only when the car is running at idle. Once above 1000 RPM, the indicator comes off. I have heard that high mileage cars should consider a change in the weight of the oil they use. Could this be my problem?
My oil light comes on, only when the car is running at idle. Once above 1000 RPM, the indicator comes off. I have heard that high mileage cars should consider a change in the weight of the oil they use. Could this be my problem?
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If you are going to drop the pan, you should certainly put in a new oil pump, clean out the gunk and check the screen. But don't be disappointed if this doesn't help.
I think what I'd do is put in the heavier oil and also as adc hints at, put in an accurate numberical oil pressure gauge under the dash. This way you really know what you have, and you may prevent a total catastrophic failure. A light really tells you only ON or OFF...you can't foresee disaster as you can with a gradually plunging needle.
if you install a gauge and you see only 10-15 lbs at highway speeds (the red light doesn't need much pressure to go out), trouble is coming soon. So rather than seize the engine and destroy it, you could have it torn down and rebuild and possibly save the crankshaft, etc.
Another remedy is a low mileage used engine, which is about a $2,000 proposition by the time you're done.
One of my clients and friend has a service garage that I will visit on Monday. He wants me to replace the car, but there is nothing wrong with it mechanically,with the body and has never been in an accident. SOmetimes it is better to stay with the devil you know as they say.
I could replace the car easily, but to be honest I don't think I'm ready to part ways yet. I will ask for my mechanics insight as well, but will definitely install a pressure gauge as suggested.
Thanks again
If the car is in good shape body wise, and you really like it that much, a rebuild would seriously be recommended, check with your local parts store, many now have re-manufactured engines, you just need the intake and exhaust manifolds, and the other bolt on stuff, from the old engine. If that is too costly, try a bone yard, they may have one with a lot less mileage on it.
Are those miles or kilometers? I know you live in Canada, just wanted to make sure.
I wold either nurse it or have it rebuilt.
And, yes, a good used engine could make sense.
but, think of this...right now, you have a 500.00 car with those miles on it. If you spend 3000.00, you'll have an 800.00 car. If it gets wrecked or stolen, guess what your insurance company will pay you?
And cars wear out in many ways, replacing or rebuilding the engine may only be the beginning.
Now, if the miles were 150,000 I might feel differently.
First of all jgmilberg, the car has 525,000 KM which actually works out to more than 300,000 miles if my math is correct.
I installed a pressure gauge in my car. Started the work yesterday, and completed today. It took a while because I wanted the thing to be placed nicely in the dash,and not hanging off of it.
After spending way too many hours installing this thing, and with the help of friend who broke a few of her nails assisting me, it was installed semi-professionally (yeah right).
I am reading 10(+/- 2PSI)in idle (800RPM), 60 PSI at 3000 RPM (100km/h on highway) and 80 PSI when the engine is pushed beyond 5000RPM. Now here is my problem.... I have no idea what the hell these numbers are supposed to be, but I have a feeling that you guys do.
As a final note, someone said that the entire car is probably falling apart with this much mileage. I would love if you could actually hear the car run. It idles solid at 750-850 RPM, burns almost no oil, and has just as much power as it did when it was new (ok,...maybe a bit less). The body is fine, except for some minor rust due to our pathetic winters. I do not want to keep the car because I am in love with it...its just that it won't die! Is this such a bad thing? By the way, it still has the original muffler, and the clutch was changed at 470,000 km for the first time. As you can probably guess this car has seen nothing but highway since new. I hate traffic.
I look forward to your insight.
80 PSI on a hot engine at 5000 rpm? I'm very dubious.
I removed the existing pressure sensor and in its place bolted on the oil line that travels directlty to the gauge via a hole I drilled in the car.The oil light obviously does not come on any longer since it is disconnected.BTW, can't you have a gauge and a light working at the same time?
When I start the car I think the pressure reading is 30-40PSI. As the car warms up the reading dips to about 10 PSI. My car has a manual transmission so in/out of gear doesn't really make a difference. How exactly do I look to see what the readings should be? My drivers manual? My Chilton repair book?
By the way, right before i installed the gauge my mechanic changed my oil to 15W-50. Kind of extreme I thought, but maybe it is affecting the pressure. The funny thing was that even with this oil, at idle the oil light came on once the car warmed up.
Some insight would be great.
Heck, just drive the thing. What is the worst that can happen? At this point the car owes you nothing.
Most Subarus I've seen seem to get real tired around 150,000 miles.
You can have both, but you will need a tee that is the same size as the threads on the sending unit and adapter. It sounds pretty tight in there, so you probably won't be able to do that. $25 dollars Canadian is not much, I think that translates to around $17 US, you flat out have a cheap gauge. Try getting one from a "hot rod" shop, look for Auto Meter, or Auto Gauge brands, they have a good reputation and are very reliable, Should cost around $35-$40 US. Try Summit Racing, they have good prices and get it to you fast. All you would have to do now is swap out the gauge.
http://www.summitracing.com
If you can determine that the new gauge or another gauge is accurate, I'd say don't worry about idle oil pressure at all.
If I buy another gauge the hose may not fit, and I may not be prepared to spend another evening in grease to carry another cable from the engine to the gauge.
BTW, the gauge has a light installed works opposite from the lighting in the dash. I used the lead from the light on the lighter but when I dim the dash lights, the light on my oil gauge increases and visa versa. Will this be solved if I switch the leads around or will I cause damage?
I think I'll switch them. I have some spare fuses. This source is the easiest to get to. I installed the stereo in my car, and believe me, I don't want to get a lead from there!
I did not know that all leads are relitively the same. This is what my query was I suppose. I will take your advise and take the hose to the store with me. I don't think they'll give me my money back on the old gauge w/o all the peripherals. Plus, I think I will spend the dough and get a better gauge. At this rate my gauge will be worth more than the car. Oh well, gives me something to do I suppose.
as for oil pressure, at idle, you can have 5psi and that would be suffecient. hold on guys before you jump and down on this let me explain..
at idle, get out and listen to your engine, if you hear no lifter or tappet or valvetrain noise from the engine you have enough oil pressure. oil pressure can change from one type or even brand of oil to another. also from one type of gauge to another. what your doing is getting a relative reading as to if it is reading presure or if it isn't. when you get in when cold with a 15w50 i believe you said, and temp is down 20deg, you'll experience higher oil pressure than during a warmer day. so don't worry so much as to how low it is, as long as it isn't rattling,knocking or creating any kind of noise out of the norm.
now, if your up in canada, i would be careful about the 15w50, what your doing is running a thicker oil and during cold days the pumpability of that oil will be very slow. (slower than a 10w40 or 10w30 for expample). anyway, the thicker the higher the pressure, and as someone pointed out earlier, too high isn't good. what that can mean is you may have a spot in the oil channels that is collapsed down with sludge and causing a high pressure side like you have on an a/c line.
this would mean less oil flow and of course engine damage. chances are i don't think that is your problem. my suggestion about oil is one don't use a synthetic, and with the amount of miles on this engine if your consuming oil, use a straight wt oil. a muti visc oil will shear down to the lower number and pass by the rings where a straight wt oil cannot. this will improve your ring seal and help your compression a little, also will reduce oil consumption. a good 30wt mineral based oil might be what i'd consider using during the winter and maybe a good 40wt during the summer.
as for the light, well i don't know how many of you are into electronics but a light bulb is a straight piece of wire incapable of being reversed wired. either way it will light up, passing electrons through it. as one person indicated, make sure you acc light increases or decreases and since your working on that circuit, i'd suggest just spicing directly into both wires on the acc light in parrallel. just hooking up to the hot side and grounding directly may not increase of decrease if they are varying the grnd side and not the hot side.
hope this helps, and i will try and visit more often. but if you want to learn or ask more about the oil situations, don't hesitate to visit the oil forum at the below web site.
bob in jville fl.
member STLE, lubricant specialist
www.bobistheoilguy.com
After I got a new timing belt, and replaced the cam and crankshaft seals I converted from a 10W-30 blended to a 5W-50 synthetic. I did notice a slight rise in oil pressure. It also started great in the winter.