Does very slow oil drain when changing oil tell me something?
 

When I changed my oil today, (engine warmed) I could not help but notice that after I removed the oil drain plug, I was waiting and waiting and waiting for the oil to finish draining. It was the longest time to drain the oil that I've ever experienced in any car I've ever had. I didn't time it, but I'd say after more than 20 minutes it was still a dribble stream.

Is slow drainage of the engine oill just a characteristic of the 300D turbo engine, or a natural function of the large amount of oil it uses? Or could the very slow drainage be telling me something?

The oil also comes out very black, but I hear that is normal in an old diesel engine.

Mine doesn't come out any faster. I usually let it sit for a few hours. Many people let it sit overnight, too.

The only thing the slow drainage is telling you is "be patient" ;)

Dear Judge:

Please remember this saying from Mr. LarryBible: "Change oil hot, and change it often".

The used oil in MB diesel cars has a high concentration of soot, which makes it very stagnant when it's cold. It's always recommended to drain the used oil after you have driven your car for 15 minutes on the highway, because hot (HOT, not warm) used oil flows very well.

Also remember the laws of physics when you change oil. You must remove the oil filler cap on top on the valve cover, and the oil filter housing cover as well as the oil filter, so that the draining does not create a vacuum inside the crankcase. The vacuum will keep the used oil from flowing out of the drain hole.
Eric

:)

Also, Eric, the oil filler cap does NOT need to be removed. The crankcase breather hose (the hose going from the top of the valve cover to the air cleaner assembly) will serve as a relief from a vacuum.

In fact, if the engine were completely sealed, it wouldn't run for very long! I guess you didn't see the thread about the engine shutting off when the breather hose is plugged up... :)

The crankcase isn't sealed for the reasons listed above, but the filter side of the lube circuit is indeed; especially since all of us regularly change the two little "o" rings on the filter stem ;) ;).

Pop the top of the oil filter up/off and your drain time will be much less. Those two little "o" rings have as one of their purposes in life to prevent oil from draining down from the filter side of the lube "circuit" when the car sits.

I'd be inclined to think letting oil drain overnight, or even a few hours, is somewhere between overkill and a bad idea. I don't like starting engines any drier than they have to be. And there pretty darn dry after sitting empty for so long I'd think.
YMMV

As has been stated here before:
" Change it hot, change it ofter."
This will get the oil to drain faster, but the rest of the advice is to let it drain overnight to get as much of the drity oil out of there as is possible.
BTW, changing it hot is a great way to warm up your hands on a cold Friday night in the garage.

definitely open the oil filler cap on the valve cover,, loosen the top of the oil filter housing, and lift the dipstick up or take it out completely while the old oil is draining.

that will make the oil oil drain faster. i usually leave it at least a 1/2 hour to drain.

change it hot and often..:D

To shorten the long dry spell after the motor is restarted:
 

be sure to follow the usual recommendation that after you put the new filter in place, but before you put the cover on the filter housing, you dump a quart or so of oil into the filter housing -- some of it will get away down into the sump, but if you're quick with getting the cap on, a lot will still be there on startup.

Interesting details... I recently changed oil in my '80 300TD (Just got it a few months ago) and was wondering why the new oil was so black immediately. Here's an idea to find out how much difference it makes if you drain overnight: before you go to bed, place a small dish under the drain hole and see how much more oil drains out during the night.

If you do your experiment with the dish, the QUANTITY of oil in the dish will not be that great. What makes it worthwhile is the fact that the last oil that comes out is the gunkiest.

Have a great day,

Suck the oil out through the dip stick
pour all but 1qt in the filter housing put
last qt in the valve cover oil opening
Roger

Wow some people here are real fanatic's. After driving the car all day I just let it drain for 1/2 an hour or so, than fill it up with 2 gallons, put the new filter in, than fire her up. I check they oil level and look for leaks before I drive it.

Slow oil drain
 

I am about to purchase my second 240D. The first thing I did on my first one was drop the oil pan to clean out any sludge. There wasn't a bit after 240,000 miles. I spoke with the previous owner, who was the original, and he advised that the pan had never been off. He said he used Pennzoil 15W40 every 3000 miles. One of the things I did while I had the pan off was to spray the inside of it with an electrical insulator paint called Glyptal. After that the oil came out like a horse doing you know what on a flat rock. Many performance engine builders have used this paint for years because it causes the oil to drain quickly back to the pan and it keeps the surfaces to slick for sludge to build up on them. Since the pan on a 240 is so easy to access and the gasket surface is completely flat it doesn't add all that much time to an oil change.

Andy

"to assure that it got oil as quickly as possible to prevent possible wear the first time it was started "--Dieseldiehard

This is what Molydenumdisulfide Assembly Grease does... you coat all those important places with it as you put the engine together... it is designed to stay there and lubricate until washed off by engine oil....