I have a 98 ML 320 with 49000 miles on it. A few months ago the dealer which services my car suggested that I change to synthetic oil. I took their recommendation and switched over to synthetic. But ever since the switch at 42000 miles the car has been using oil. I have put in 2 1/2 qt of mobil 1 since that time. Iam going back to the dealer next week for another service, should I notify the dealer? Is the oil consumption normal? Thanks for all replies.

That is not normal consumption in my opinion. You also have about 1000 miles left on your warranty, so if the oil consumption is a result of some sort of engine damage, get that fixed before it ends up coming out of YOUR pocket.

Insist on a thorough checkup. Otherwise, the dealership may count on you "lapsing" on your warranty, and not pay for the service...

I don't think using a quart of oil every 3K miles would be considered excessive under any warranty program. About the only thing the dealer will do is look for a leak...other than that I think your other option is going back to dino oil assuming of course it didn't use any before you switched to synthetic.

Guys,

Is the whole reason why MB dealer recommonds ML owner change their oil to synthetic is because of the error in the program that alerts you when u need an oil change is faulty? Instead of alerting you every 5k miles, it does this ever 15 k miles, which is kind of excessive for any oil change interval. So it wouldn't be necessary to switch to synthetic, right? Just change it every 3k miles will do okay?

vutown

There has been lots of discussion about this subject. My ML has minor leaks after switching to synthetic. It bugs me more that it's dripping on my garage floor than anything else. Some people have been told by MBZ that it's normal to for the ML to use a quart every 1000 miles! Imagine that! I don't think it's normal for ANY car to use a quart of oil every 1000 miles. For some cars with a 5qt capacity that's an oil change every 5000 miles. Check out this thread...

http://www.peachparts.com/shopforum/ml-gl-g-wagen-r-class-unimog-sprinter/18745-199-ml320.html

Kuan

Sorry to hear about the problems with your ML. The statement I got on my TE was that oil consumption up to about 1 quart every 800 miles is considered acceptable. BTW my TE was going through oil at a rate of a quart every 600 miles, with about 70 K miles on the odometer. They fixed the valve guide seals and that reduced the consumption to a quart every 1,500 miles. They refused to do further fixes.

Still, it’s odd that by changing to synthetic you would have a sudden and drastic change in the behavior of the engine.

Perhaps the change freed up some gunk and some of it got stuck somewhere?

Had you previously followed the FSS? If so you may be among the many with early engine failures complements of Mercedes “reduced” maintenance intervals.

Do you drive a lot in the city or do a lot of short trips?

Anyway, defiantly notify the dealer as well as MBUSA. The more noise you make the better the odds of getting the problem fixed.

Regards

I found it strange also that a sudden change to synthetic would cause this. I had previously not followed the FSS schedule, but changed oil between 5000-10000 miles. And before the switch over to synthetic, not use a single qt of oil. Thanks for all the replys.

Major,

What weight of synthetic oil did they put in?
What weight of dyno oil were you using?

I have a 98 E320 (same engine as your ML320) that I swiched over to Mobil 1 15W50 at 70,000 mi with no loss of oil. I also change my oil & filter at 3,000 mi intervals.

1 quart per 1000 miles is acceptable.

Notice the quotes around that statement? I do not mean to quote Stan directly, but secondly (via MBNA). Technically, they say 1 qt per 1000 miles is acceptable. But I have a 1995 C280 M104 with and I don't burn any oil (1 exception: partial switch to synthetic), and I drive quite a bit on the highway at high RPMs (4,000 +).
So, yes, your oil consumption does fall under the "normal" standards, but get it checked before the warranty is up! Tell them it's burning 1 quart every 700 miles! I would do this because I would not find that kind of consumption acceptable, or not on an engine with less than 50,000 miles, no matter what MB says.

I think oil burning under any circumstances is unacceptable. I would get that checked out under warrantee. I remember when my 190 started to burn 1qt/1000mi, it only deteriorated to 1qt/500mi. In the process the excess soot & raw oil clogged my pre-catalytic convertors. After new valve guides & seals haven't burned a drop for the last 170,000mi. Granted this might be a special case since the early 190's had notoriously poor valve seals. But I worked with an 95 Audi A6 2.8 whose healthy appetite for oil plugged both catalytic convertors with only 100k on the odometer.

Official policy is that an oil consumption test must be done by the dealer using only the recommended oil. 1 quart per 1k miles is ridiculous. Ask them for the exact reference and the DATE this standard was adopted! It was acceptable in 1955, not in 2001.

Kuan

I asked my independent tech, who left the dealership after 14 years, what he thought of the M-class. Other than the well-known quality issues with the 1998-9 models, he said they had replaced a set of rings on one under warranty, which he directly attributed to the owner following the FSS oil change frequency.