My 2000 ML 430 used a 1 Qt of oil every 900 miles or so. This vehicle had this problem since it was new. The dealer I purchased from informed me that it needed to be broke in. However, it continued. I put up with the problem until just recently. I took the vehicle to the different dealer and they are attempting to correct the problem by replacing the rings. I am not sure just what all they are suppose to replace. How can I find out what they are supposed to replace? I believe the ML was not built with top quality in mind. They just put together a car. I like to see the ML build their vehicles like the Toyota Landcruser or Lexus.
I recently purchased a 1999 ML 430. It was fine on the test drive, but after the purchase the check engine light came on. The code indicated the EGR valve. I purchase a new one and started the repair myself. After removing the the old one, I found the the small rubber hose going to the engine was broken, and caused the EGR code due to a vacuum leak. I replaced the hose, cleaned and put the old EGR valve back on, and had the check engine light reset. The problem was solved and about $500.00 saved in about 90 minutes worth of work.
The ESP light comes on periodically, but after a few starts goes off.
I do have squeaking in the rear. I was told the shocks need replaced about $1000.00 (never). I will purchase the shocks and have them put on. They are not leaking and the ride is great. I think it's bushings or the ball joints, which can't be lubricated.
I replaced the Bose with Kenwood DVD and EQ, used the Bose amp and speakers sounds great. I will replace the speakers and amp next summer; it's a lot more work.
I will have to do the brakes and rotors before winter.
I have not had any oil consumption problems so far, the truck is fun to drive.
The biggest problem is the rear locks not working; they continue to click after you hit the lock button on the remote or in the truck. The actuators will probably need replaced; common problem with ML's.