I am still a relatively new owner of an 87 300SDL and have a question about the low oil light. I am about 2100 miles into my first oil change and the oil level has gotten down to about a 1/3 of the way up between the min and max marks on the dipstick. Since I plan to change the oil again in another 900 miles (two weeks), I didn't want to add much oil at this point. But, I noticed yesterday the low oil light would come on occasionally. Since I drive about a 100 miles a day, I didn't want to risk anything and put another ~3/4 quart in it last night. I guess my question boils down to is this sensitivity normal in the low oil sensor, or is it possible my dipstick reading wasn't accurate (it was level and had drained down a minute or two when I checked it), or is that level really too low to run the engine on?

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There are two different failures that afflict the low oil warning light. One failure involves sludge (?) accumulating in the sensor and this can be cleaned or the the sensor can be replaced. I have found that on every diesel I've tried it on, changing to Mobil 1 or Delvac 1 oil has cleaned the sensor within about 5kmi (that did NOT work on at least one gasoline 300E though it has worked on a couple).

The other failure is of the 60 second delay that is designed to prevent momentary activation of the light when turning left, accelerating or decelerating. This 60 second delay has started failing on MANY '86-'87 300D/TD/SDLs. There is doubtless a specific part of the delay circuit that fails, but I have NOT yet determined which part. Replacing the entire left side printed circuit board (the one on which the temp, fuel and oil pressure gauges mount) or the little daughter board attached to the main board with a good used one has resulted in curing the problem, but these will doubtless fail soon as they are virtaully the same age.

Marshall

This is common on the '87's especially on left hand turns. If you always turn to the right you probably won't have this problem.

Mine does this even though the oil is at the correct level. Check often and change frequently.

Regards,

Joe

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1987 300TD 440K - My car
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Thanks guys for the information. I noticed today at lunch the coolant light was coming on, and the low oil light is not coming on now. The coolant level may be a tick low, but it was lower a couple weeks ago and I did not get the light. Sounds as though I may have a goofy electrical issue. Thanks again for the help.

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Keep everything as simple as possible-but no simpler--Albert Einstein