mis3

I frequent 2 dealerships and for both places, they change oil from extracting the motor oil from the top.

I am curious. I understand that for w209, there is a drain hole in the bottom. Isn't it beneficial to let the old oil to fall out by gravity? This way, all the accumulated sludge and deposits will be drained out as well.

M-bENZ

Your choices.

Glyn M Ruck

As long as you use the correct oil & drain intervals there will be no sludge dropped out. Sucking from the top is fine. Maybe at 150K miles a bottom drain once would be a good idea just to check. You just have to drop the engine protection plate. Have you owned the car from new? Do you know it's entire service history.

Rudeney

I prefer top side - it's much cleaner, plus no crawling around on the floor. I use a MityVac, which then makes it very easy to transport the used oil to the recycling facility (i.e. the big oil vat in the back room of the local Advance Auto Parts store).

mis3

i did buy it new and I do have the entire service record.

Since my car is always serviced at the dealership, I do not have to handle the used oil.
I found an indie recently and he prefers to drain the oil from the bottom. I may give it a try with the ATF partial flushes.

Glyn M Ruck

I too like sucking from the top. If you have used the correct oils & serviced from new at correct intervals I'm sure you have a nice clean engine & the oil will have kept all the crap in suspension. It's your choice. If you do a bottom drain please tell whoever does the job to be careful when replacing the skid plate not to overtighten the retaining bolts. Ham fisted mechanics are always stripping the threads the bolts go into. Then it's Heli-Coil's and all that cramp.

mis3

If drained from the bottom, should the drain plug be changed?

Glyn M Ruck

Yes- The drain plug is microencapsulated with a sealer.

If you want to reuse the old one you can seal it with a suitable Loctite or similar product.

With cars on Mobilodrive Maintenance plan Benz just throw them away.

bheng

i do it from the top: easier, not much of a mess, and no need to be under the car.

mityvac for the win.

M-bENZ

Mityvac oh yea...

lkfoster

I do mine from the bottom. On the V-8s the oil pan has two drain plugs due to a configuration that has to clear a cross-member. Draining from the top leaves something like a liter behind.

mis3

Finally someone who drains from the bottom.
Do you replace the drain plug? How much are these plugs?

lkfoster

Drain plugs no, but copper seal rings yes (the cheapest part you'll ever buy for a Merc).

Maybe you're supposed to change drain plugs, but I'm old school. I only change drain plugs when the threads get messed up which mine were not. From what I could gather from the million ft-lbs of torque that mine were tightened to I don't think that the dealer ever drained the oil from the bottom.

Glyn M Ruck

mis 3 - the first time you undo a plug it can be tight due to sealant on the threads. A new crush washer & a quick paint with sealant is all you really have to do if you want to save some money. The plugs are not expensive if you want a new one. Up to you. There is no right & wrong here IMHO.

mis3

So, the plug comes with a big screw and a crush washer, right?

As I said, this is the first time I go to an indie. I have to make sure all are done properly.

Glyn M Ruck

They come separately

Plug $1.53



Washer 17 cents

mis3

The indy did the oil change for me yesterday. He did the oil change from the bottom and he put in 7.5L of Mobil-1 0w40.

I ran the car. I stopped the car for 10-20 minutes and let the oil to get drained down to the pan.
The Check Oil Level in the display said OK. However, I went to dyno mode and at startup, the oil level said 7.0L. I recall that it used to say 7.9L at startup. Not sure how accurate is this oil level in dyno mode.

Should I put more oil? I was there at the oil change and he did put in 7.5L !

I just checked the owner manual. For my car, the oil capacity is 8 L.

M-bENZ

If the display said "OK" ...i would leave like it is.

Yidney

I think it just takes longer than 10 minutes to drain. When I first did mine I thought my dipstick was innacurate. I even posted here about it. By morning it read exactly where it was supposed to.

Yidney

What V8 has two drain plugs? If mine does I missed one. I do mine from below only becuase I can't see the end of a pump tube, so I don't know how much I'm leaving behind. No way you can get every drop from above that a drain from below can. May be ****, but I'm Ok with that.

lkfoster

My C55, which I believe has the CLK front end, has two.