The shape of the bottom of the pan appears to allow all but the very last 1/16" of oil to escape via the drain hole.

I'm absolutely positive that a vacuum assisted device cannot get down below 1/8" due to the failure of the tube to sit squarely on the bottom of the pan and the potential for drawing air around the bottom of the tube at the point of 1/8" submersion.

I use a topsider to change the oil in both my transportation mobiles, a '95 300D and '02 LB7 Duramax. I've done a test on both cars where I remove the oil plug let it drain until nothing is coming out, then I put the Top sider in & I am still able to get more oil out. So, for my own personal satisfaction, I know that I am able to get more oil out with my Topsider.

I've got the same pan that you do, Brian. You're right. It drains all but the last 1/16 of an inch or so anyway.

And since we rotate tires every 5,000 miles with our oil change (like the owners manual recommends), I take care of that last 1/16" by just jacking up the right front first and letting it sit like that for a minute or two before I jack up the left side. Works great.

No matter which method we use, we're still talking about mere tablespoons in two gallons.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

I agree.......it's not worth arguing over the remainder.........there's more than one pint in the cooler.........and I'll usually drain that.

I remain unconvinced that a topsider can honestly be successful at removing more oil than the drain plug.........unless the vehicle is at a slight upward angle and the position of the dipstick is closer to the rear of the pan. Return the vehicle to a slight downward attitude and the drain plug must win every time.

I'm nervous about draining the cooler because "What happens when one of the bolts wrings off or a line breaks" - may not be an issue but everything on mine seems to fall apart if you mess with it too much. Even that pint doesn't worry me... basically because I change so frequently. Uses between one and two quarts between changes at the moment so it gets replenished that way too.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

I agree. I don't advise anyone to screw around with that cooler line.........way too much risk of a costly "problem". I did it.......took the risk once........was successful........and now I can routinely crack the line without any danger.

The SD has new lines........so, maintaining them is not a problem.

OK, I'll chime in here too
There is little oil left in the bottom pan, but its a lot less than what resides in the oil cooler and associated hoses running to and from the filter cannister.
One thing I can do with my home made Topsider is stick the tubing into the oil filter cannister, way down into the bottom there is a recess that is part of the line going to the cooler and suck some oil out of there. I've even put the tubing into the oil filler opening on the cam cover and sucked an ounce or two out there

I used thick walled Teflon tubing because I like its stiffness and I can suck out really hot oil oil (initially I was using 1/4 in poly (water) hose and it was way too soft!)
I cut the end of the tubing at a bevel hoping it would fit tight against the bottom of the recess in the pan but then realized that a few ounces here or there isn't worth the effort to drain, all you guys trying to get the very last drop out of the engine are purists wasting your time, its no big deal having a little dirty oil when you are going to dump almost 2 gallons of fresh oil in.
Do the percentages thing. First lets presume there will be 4 oz of oil left in the pan in or around the drain area.
1 gal is 231.0 cu in. There are something like 7 qts = 433 cu in of oil in a full engine (including the filter) so 4 oz out of 433 is like only 1% of the whole. There is probably more than a qt (57.75 cu in) of oil left in the cooler, greatly overshadowing the trivial amount at the bottom of the pan. I liked the old 115 300D with a drain plug at the bottom of the oil cooler, why couldn't they keep that one? Don't get all fired up thinking you'll drain some oil by removing the cooler lines because they are usually stuck due to damn aluminum-to-steel alloying over time and you will wipe out the threads on the cooler when you remove them (unless you used anti-sieze on the threads like I did when I replaced mine after destroying the cooler on one of my 603's. I am sorry to say I've BTDT!)
I confess I still use the bottom drains on 617 engines, its easy and sure and you can walk away and let it drain while you do other "stuff" like inspecting the brakes, rotating tires, etc.
It's the later models with the lower covers that are a real PITA to change oil and frankly I'm getting old and lazy and I find its a breeze to use my Topsider so I am favoring that method. Afterall thats what they do at the Dealerships !
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

I've used a Topsider on the diesel in our sailboat for many years and it works great. I'm going to start using it for the MB's because a couple of years ago I had skid plates made for both cars and now it's a pain in the butt to drop the oil.
Wonder why I had skid plates installed? Look at the oil pans of most old MB's.

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Houston, Texas
1984 300CD 235K miles, Elvira, one owner
1987 300TD 180K miles
1974 TR6 78K miles Sarah Jane, one owner
OBK #27

When I put the belly pans back on the SDL you can bet I'll be using a Topsider! I'm not removing a ton screws and playing with some big plastic pans everytime I need an oil change.


But right now the SDL is nice, I don't need to jack it up! Just reack under with a wrench!

On the newer cars removing the belly pans is a major PITA, more trouble than its worth.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200