I have a 98 ml320 with almost 130k. It has been changed with regular oil 20W-50 every 4-5k regularly. In the last year or so, it consumed abut a quart in between oil changes. I read the post on switching to synthetic. So I used 15W45 Mobil one. With this new synthetic, the engine consume a quart immediately after about 1,000 miles. I filled it up with more synthetic oil and after another 1,000 miles, another quart is consumed. The engine runs fine. There is no missing. I don't think there is fouling of the plugs. This worries me. Do I have worned rings or valves? Planning to change back to regular dino 20W-50 and back to regular 4k changes. If consumption is still high, I will probably have to trade it in for another MBZ(?) or other. I was hoping to get 200k on this truck. Any thoughts or experience out there?

John

Here is my story. Barry owned the 1999 ML320 from NEW. It used a quart every 1,000 miles since NEW. the dealer told him that was normal/not uncommon. Barry thought it was BS --He bought a New 2003 Lexus and sold me the ML320 for trade in value. (85,000 miles +-). 17,000 miles ago.
So..
I cleaned the EGR Tube, burned premium (Barry used regular gas) , ran 3 bottles of gum out emission control cleaner in it and believe it or not...Now it goes 4,500 miles until it needs a quart of Mobil One.
I submit to you that one or more emmission control stuck or plugged valves/tubes/passages can cause it.
If you dont find the cause.. I would bet you can drive it another 100,000 miles adding a quart every 1,000 miles. When I bought mine thats what I was prepared to do. I just got lucky. Good Luck.
WalMart has 5 qt Mobil One Bottles for under $20.00

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

Hey Steve,

Maybe you are bringing a good point here. I have heard that most the ML oil consumption problems are sudden and at early milage (70 - 90K miles), which is not consistent with engine components wearing out. Or like in your case, since new, and not getting worst overtime. I am not an auto technitian, but as an engineer, it looks to me that these sudden changes are not due to internal components wearing out which should show some signs on something that is working fine. Maybe there is something prone to get stuck, sticky or so, unless there is a broken part which may be obvious.

My ML has never used any oil, until now at 83K miles

I check the oil level frequently, say every 2K miles. Last oil change went, and at about 8K I checked using the cluster, and verified with the dipstick and needed 1 qt to my surprise. I topped it, and now it is time to change the oil at 10K miles, and need almost another qt. I know this is not excessive, but it is sudden and with the new oil change I like to monitor it to see if it start to get worst, stays the same or goes away. I do 90% highway driving averaging 75 - 80 mph.

I am changing the oil now with what I used all along since 26K miles, mobil1 15w-50. The first 2 oil changes was dino 15w-40 at the dealer. I will keep monitoring now.

With what I have read, I don't think I will use an additive, although most of these additives are just a higher concentration of the same additives we get with good oil and good gas. I'll maybe do just an "italian tune-up" and see what happens.

Although the ML sudden oil consumption problem is a well discussed problem, it don't look like is as frequent as to be considered a cronic problem. Looks like there are much more ML's with over 100K - 150K miles running than rebuilt engines around, at least based on what I read here. I don't want to think that there should be many engines were rebuilt by the dealers when this may have not been necessary, if this is the case.

I am not an expert, these are just my comments, still I think Steve has brouht a good point that may merit some discussion.

Rene
'99 ML 320

I did have a problem with the EGR tube; gave me a CEL. After I cleaned it, the light went off. The idle still as not as smooth as I would like it. The car doesn't die now. Does this mean that I need to continue to keep cleaning the EGR tube or replace the EGR valve completely? Also, I haven't kept up with Techron with the gas(I use 93 octane exclusively).

Thanks,

John

P.S. What about using dino vs. synthetic? It seemed that switching to synthetic recently exacerbate the problem.

I would start by not topping it off. from the add line to full is 2 plus quarts. The top quart will leave the engine easier because of windage, frothing and and carryover. When mine turns the add oil light on, it is always down at least 2 quarts. But I never fill it when I change oil and I only add 1 quart when the oil light comes on. I am getting about 4000 miles per quart an my 98 ML320 has 130.000 miles. I have followed this procedure for over 25 years on my diesel powered Benz's.

Jim