"reduce oil level" indicator light and smoke after oil change -- mercedes clk


I got my 2005 Mercedes CLK serviced recently. After driving 20 miles or so the “reduce oil level” indicator came on. In somewhat of a panic – I knew they had over-filled my engine – I drove a half mile home. When I got out of the car I noticed a moderate amount of smoke (the oil burning kind) coming from somewhere in the engine. I brought the car back to the mechanic. they claimed that they had only over-filled by a half quart (9 quarts instead of 8.5); they “corrected” the problem and returned the car. So I’m driving today AND THE LIGHT COMES ON AGAIN! Now they claim that it’s a faulty indicator and they want to charge me to fix it! Well. What do you guys think!? I know what I think.




I think I know what you think and I think what you think is what we both know.


I would have the oil level checked ASAP, I suspect they failed to properly install the oil filter cover and created an oil leak at the o-ring that seals the cover. That would explain the oil smoke and the low level. If it is losing oil, you do not want to drive it without verifying the level. It seems unlikely that the sensor coincidentally failed. What kind of a shop did this service?


Thanks for the response! The shop is a highly recommended “import repair shop” (not the dealer).
…I thought that “reduce oil level” meant that there was too much oil, not that it was low (?).
But I like your theory.



I’m not sure on your car, but either way you need to have it checked and corrected. It seems strange that overfilling by half a quart would cause any smoke unless they somehow created a leak.


Nice consequence of Mercedes stupidity in omitting dip sticks !


There’s no oil dipstick?


I don’t see how a paltry 1/2 quart of oil would affect anything. My feeling is the smoke was due to some oil being inadvertently spilled rather than any overfilling.

As to the oil level indicator that’s impossible to say without a diagnosis. I’m not familiar with the oil level indicator on this vehicle at all but if it’s not involved with a filler cap in any way then I see no way it’s the shop’s fault the indicator went bad.

The only thing I can think of would be if they overfilled the engine by more than 1/2 a quart (say by 2 or 3) and possiby lied to you about the amount. That still doesn’t solve the indicator mystery and without detailed knowledge of how this works I can’t be of much help. Many indicators on other cars simply work as a common float and contact type of thing and they’re sealed units which cannot be tampered with.


Yup - Mercedes and BMW have deleted dipsticks - except from their engineering depts !




I was surprised there was such a thing as a “reduce oil indicator,” but apparently Mercedes added it as a precaution since there’s no dipstick. A website I found said that the indicator is very sensitive, so it’s possible that 1/2 quart might have set it off.

I was thinking that perhaps the shop you took it to has the wrong oil amount to add in their book, or else like OK said they overfilled it by a lot and it’s still overfilled now. You may want to take the car someplace else for an oil change and see if the problem goes away with a fresh drain and fill. $40 for an oil change is a lot less than a few hundred to fix an indicator that may not actually be wrong.


It’s great reading all of your replies. I really appreciate them. I’ll post what happens after I take it to the dealer for a prognosis.