I've been driving my 68 Dart - 225cu in, every day to work and back about 60 miles. Its been doing fine till today.

This morning I fire it up and head to work, but everytime I let the engine get below 1000rpm, the oil light comes on.
I went ahead and drove it to work, I figured it was a little low on oil and i'd check it when I get to work.

Well I let it sit for while, just went out and checked the oil, and its right on the full mark.
So,, any ideas as to why the oil light would be coming on at idle ?

Thanks

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Possible reasons,

Low oil pressure, Bad sending unit for the oil light.

You could replace the sending unit, but I got a gauge so I could 'see' what was wrong. An oil pressure gauge isn't very expensive or difficult to install.

Unfortunatly, my gauge confirmed that the oil pressure was very low at idle. Here are some of the easy things to do to try and improve.

If your motor has hundreds of thousands of miles of wear and tear, it might be time to replace rod bearings or more. A high volume oil pump might keep the pressure up for a while. Before giving up hope for this current engine, or if it's low mileage and running strong, try the following.

Change the oil and filter, try using thicker oil (I use 20-50 in really worn engines) and possibly some additive (Lucas makes a product which has been reccomended to me many times, but I'm just too cheap to spend $7 on a quart of it)

If your pressure is lower than normal all of the time,(hard to tell with a light, but easy to understand with a gauge) you can shim the oil pressure spring in the pump. This is not very difficult to do and does not require oil pump removal or engine lifting on models that I have worked on. I don't suggest you try this modification unless you have an oil pressure gauge to see the results. This has shown 10 lb or more improvements at higher rpm, but didn't help hot idle pressure on the worn out motors I've worked on. I won't explain the procedure unless you want to try it.

A replacement oil pump would come next, but It's a poke and hope solution at best. I've never replaced 'just an oil pump', so I don't know how much improvement it might make. You could try a high volume replacement pump.

Running the motor with low oil pressure is a sure-fire way to kill it. In my opinion, stop driving the car until you've done the pressure tests or plan on replacing the motor soon.

I've had 2 slant six motors with low oil pressure problems, both started knocking after about 1000-2000 miles of driving on the heaviest oil I could find. The most recent was my Aspen, I knew the pressure was unreasonable low at idle, I drove 400 miles to clay city, raced it, and it started knocking at 80 mph on the way home. Still finished the trip home without a failure, but I slowed it down to 60.

You've got some time, but I suggest you use it wisely.

Finally, I could be completely wrong. This is simply my experience and others might have better suggestions. I'm not a trained mechanic, but I've been tinkering for a number of years now.

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1980 Aspen 225 super six

That happened to me a year ago, but It lighted when I maked closed turns, just check oil bulb (located at oil filter base), meaby it is loose or you need to change it.

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Mopar Muscle is well defend by Slant Six!

Valiant Duster 1971

This also happened to me with an Aspen I once owned. I changed the oil and filter and problem solved. Yours might not be that easy, but it's worth a try.

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

The two logical sources is a sending unit or a worn oil pump. How many miles is on the car. I bought a 74 Dart Sport with fresh rebuilt engine in it when it got hot the oil light would come on. Talked to the person who rebuilt it and he said he should have put a new oil pump on but he did not. I put a new oil pump on it and solved the problem. But changing a oil pump on a slant engine in the car is not fun. Taking it on and off is no problem but to get the clearnece to do that is a nitemare. Thanks Ron Parker






Hell Hath No Wrath Than A Possum Scorned

This may seem a bit stupid, but I had the same problem. As it turned out, the wrench monkeys at the quickie lube didn't re-connect the wire to the sender. When the loose wire would contact metal in the engine compartment, the light would go on and I would panic. One hair raising car ride and I isolated the problem and "fixed" it. The funny thing is; the next time I had my oil changed (at a different place) they "forgot" to re-connect it again.

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

UPDATE:
Well, I changed the oil and filter yesterday. (first time since I owned the car). And refilled with 20w-50w

Problem seems to be solved at least for now. Driving around yesterday, and driving to work this morning, the light never came on once.

I also installed a set of the Autolite 985 sparkplugs. Car seems to be running great. Cant really say I feel any difference in power or anything like that, but i'll be checking my milage this week to see if the plugs made any improvement in gas milage.

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