My dad always takes his car to the dealer for all scheduled maintenace, and I have noticed that the dealer always overfills the engine oil by exactly the same amount. It is always about 1/2" to 5/8" over the "full" mark. My question is that is this amount of overfill not enough for the crankshaft counterweights to get into the oil and cause foaming, or should this excess oil be siphoned. The car holds 7.4 quarts and the service receipts always charge for 7.

Does 7 quarts put the oil level over the full mark by this much or does the dealer know something that I don't. Why would a bery reputable dealer put too much oil in? Also, there seems to be no mention of any low oil pressure warning anywhere on the 97 C280. Did MB omit this piece of information or am I missing something.

-Thanks for any replies, I know this topic has been covered many times already.

[Edited by Ali Al-Chalabi on 06-20-2001 at 11:57 AM]

I don't think it is very wise to ignore the manufacturer's specified capacity. I think a couple of ounces of error is okay, but a half quart? Foaming is only one potential problem, as I had a friend's car blow out the oil seals on his Bug when Jiffy lube did just that.

Sounds like they round off and use 8 quarts instead of 7. Not sure why, but you probably should challenge the dealership.

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

I don't know what volume of oil the engine is overfilled by. The distance between the min and max marks on the dipstick is about 9/16 of an inch and this is supposed to correspond to 2.1 quarts. I was referring to the oil level of the dipstick being 1/2 an inch to 5/8 of an inch above the full mark. If the level is directly proportional to the volume of oil at this part of the sump, that would mean a 2 quart overfill! The car now has 65,000 miles and has had the correct amount of oil in it only once, when delivered from the factory.

Regardless of the amount or reason, there isn't a good reason to overfill the crankcase with oil.

Okay, I can think of two:

People who store cars for extended periods (years) sometimes completely fill the engine with oil to keep the idle parts from slowly corroding themselves to each other. Then periodically the engine is spun manually to move the oil throughout the different components.

My Bug, which takes 2 1/2 quarts of oil now takes 5 quarts...but now it is fitted with a deep sump oil pan which holds an additional 2 1/2 quarts.

If your situation doesn't fit these two cases, overfilling is likely to cause unnecessary engine damage in the future.

Again, confront the dealership about their reason for doing this. Then tell them to cease and desist!

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Thanks for the replies, those were exactly my thoughts on the subject. I will ask the dealer for a reason.

blackmercedes-

That is exactly what I am afraid is going to happen. However, the car is my dad's car. He just drops at the dealer, lets them charge him whatever they want and do whatever they want to the car, unfortunately. Who is he going to trust, trained MB mechanics or an 18 year old?

The car has so far logged 65,000 miles and is out of warranty. It has NEVER had the correct amount of oil in it, the lowest I have ever seen the oil level is 1/2 inch above the full mark. I just hope that its not enough overfill to cause any heavy foaming. Unfortunately, the level will remain overfilled because the dealer does it and they know everything in his eyes.

My car always has the correct level because I do it myself.

Sometimes it is better to trust a loved one than a stranger.

Does your father respect your expertise?

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Never asked him about the oil level. He sides with the dealer on never changing the tranny fluid, though. And usually keeps his cars for a long, long time. Plus, I'm away at school most of the year, so I can't be home to siphon the excess oil after every oil change.

It's possible the car holds 7.x qts and they're simply dumped in a full 8.0.

Alot of shops have moved to automated equipment vs. the qt. at a time thing. It's faster and there are ecological considerations. The problem as I've been told is that some automated devices have a residual amount of oil left in the hoses. The tech sets it for x number of qts. and you end up with that amount plus what's left in the hose.

A fellow I work with recently had one of these "automated" oil changes done at a Toyota dealership. Two blocks down the street his engines started smoking. It turns out the dealer installed an EXCESSIVE amount of oil.

My guess is that in most cases this is simply user error...somebody is not thinking/paying attention.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

According to the manual for my '96 C280, it takes exactly 7.0litres or 7.4 US Quarts. This is correct if you do oil and flter (I put in exactly 7 litres when I do mine and it takes it right to the full line). I would talk to the service manager and ask him how the oil they add is measured. It's a remote possibility also that they do not change the filter each time, but add oil as if they did.

Guys,
Just a shot in the dark. Perhaps the dealership knows about this and fill the car with 8 quarts anyhow, because they might not want to deal with the 7.x quarts of oil. Also, they can justify the charge of 8 quarts versus the 7.x quarts of oil. Perhaps a rule that they go by? in any case, they're irresponsible for overfilling a car with oil.



-regards,
Vu

That's one thing that is interesting, they only charge for 7 quarts on the reciept, but there is no way that there is only 7 quarts in the engine, also they do change the filter. I will try to take it up with the dealer today.

Most cars will tolerate a 1/2 quart overfill without problems. For a car that consumes oil a 1/2 quart overfill will provide an extra margin of safety for people who seldom check their fluids. That is usually about 1/2 inch up on the dipstick. Also, make sure your car is level when checking. Even a slight tilt can make a big difference on the dipstick.

The problem may be the result of the old oil not all being removed prior to putting in the new oil. This could be caused by the dealer not allowing enough time for the oil to drain back into the crankcase prior to draining, or by a failure to remove all the old oil using the suction method. When the new oil is added, in the correctly specified amount, it adds to any old oil left in the crankcase and will show as overfilled.

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Tom H.

My car was continually overfilled during oil changes until I stopped going to the dealer for the service. When I brought it to their attention, the service rep said that it wouldn't hurt anything, but that they would drain some out if I wanted them to! That epitomizes my experience with those folks.
Steve