DCF

If you wish to continue to drain the oil, I would recommend that you replace the crush washer under the bolt with every change. It is designed to seal the mating surfaces of the pan and plug. They used to be included with the filter but now I believe you have to purchase them seperately.

I used to drain the oil the conventional way, but then I realized suction is the better way to go. The drain method shoots oil onto rubber suspension parts (not good) and I never could figure out why the drain was on the side of the pan, as opposed to on the bottom. Protection, I suppose. Anyway with the plug located a 1/4 inch up the side, draining doesn't remove all the oil anyway.

The most important rules to adhere to are :

Always run the engine for a few minutes to warm up the oil and keep the contaminants in suspension.

Use a quality 0W40 synthetic motor oil, such as Mobil One.

Use one of the new "fleece" type filters and replace all four O-rings on the housing.

DO NOT OVERFILL.......The range on the ML dipstick encompasses approx two quarts. I purposely leave my ML about 1/2 quart shy of totally full, so that I can get a more accurate reading on the dipstick.

Once you purchase and use one of the suction devices, you will be a believer. Much easier to recycle also, since you have a reservoir you can pour out of instead of a huge pan. My 99 ML430 is approaching 250,000 miles and I attribute this remarkable mileage primarily to synthetic oil changes every 10,000 miles since day one.