khaug

Hi all. Can any knowledgable person help with locations of front and rear jacking points for a floor jack, so I can put the car on four jackstands to change the oil?

Thanks.

electric blue

No disrespect but why on earth would you go through the hassle of jacking your car up and then letting it down on jack stands just to change the oil. If it were me I would take the car to a garage in your city and have them do your oil change. Just my view.

stox

Personally, I would recommend getting a topsider. Faster, more convenient, and the oil is already in a can for recycling when you're done. No need to jack up the care, no need to remove the mud shield. I have also heard some say that the suction of a topsider pulls more crap from the bottom of the oil pan than just draining it, but I have seen no data to confirm that.

khaug

Doing an oil change requires only a trivial amount of work, IMHO. Doing it myself insures that the job has been done right, saves money and gives me the satisfaction of having avoided a trip to the dealer.

I've heard nothing good about the legion of gadgets that permit removal of oil through the dipstick tube. Specifically, they inevitably leave behind an undetermined quantity of dirty oil and cannot remove the particulates that have sunk to the bottom of the pan which get flushed out with a regular crankcase drain. This from a study done by either the TUV or ADAC (can't remember) years ago when Germany was considering banning crankcase drain plugs in the belief that doing so would improve disposal of waste oil.

I'll stick to the traditional method, thank you, but I need to know how to do it right.

vinceC

For many years M-B has designed their engines to be sucked using the dipstick tube itself (not just sticking a tube down the dipstick tube). On the cars without a dipstick there is a specific oil evacuation tube. This system actually extracts more oil than draining through the plug. However, I am too cheap to buy an extractor, so I use the plug. On my E430 I am able to remove the plastic undertray and the drain plug without jacking up the car. Quite easy actually.

When I do lift that car I use the crossmember at the front of the subframe. I use an oak board to distribute the load. At the rear I lift under the differential. You car may be different. Be careful in assessing where to lift.

mleskovar

my .02.....there is no way a suction tube can drain more oil than the sump plug. It is physically impossible. The tube cannot reach/touch the bottom of the sump or the suction stops. If the end of the tube is cut at an angle to avoid this problem then the angle of the cut determines the lowest level that can be vacated before it sucks air. 100% removal of oil is not possible with either method but draining is more effective.

scorchie

Well, VinceC's statement was that the engine was designed to have the oil evacuated via an evacuation tube, not a tube down the dipstick tube. If the engine is designed to be evacuated by vacuum, it is quite believable that this method will remove more oil than simply draining it (as it appears that most drain plugs seem to not open at the lowest point of the pan, they tend to be in an angled part of the pan, which means some oil still remains below the lowest point of the drain).

So, it's not physically impossible.

-s-

Hackman

I think in a properly designed oil evacuation tube system it is possible to drain out more oil then using the drain plug if the car is on a level surface.

If I had to come up with a design for a system, I would add a small depression at the lowest part of the oil pan about the size of a quarter and maybe an 1/8" inch deep and center the oil evacuation tube on the depression with about 1/8" clearance between the bottom of the tube and the depression. If the car is on a level surface, all the oil will flow into this small depression and be sucked up and out of the tube.

I think this is actually more effective then a drain bolt because of the way the engines are set into the chassis of most modern cars. The oil pan is the lowest part of the engine, and if you place the oil drain bolt on the bottom of the oil pan where you can get the best drain on a level surface, the head of the drain bolt becomes the lowest part of the engine. This becomes a liablity when you want to set the engine as low as possible in the chassis. Most engines have moved the drain bolt from the bottom of the pan to the side or back of the pan in order to improve the profile of the engine so the engine can be set lower into the chassis.

By moving the oil drain bolt away from the bottom of the oil pan, it is now impossible to get a complete drain of the oil if the car is on a flat surface. Things change however if the oil drain plug has been moved to the back of the oil pan like on some japanese cars. I haven't seen the oil drain plug location on a mercedes so I don't know if it is on the back or side of the oil pan. If the oil drain plug is on the back of the oil pan facing the rear of the car and you jack up the front of the car, the oil drain plug hole does become the lowest part of the oiling system and a complete drain of the pan is possible.

So for the dealer with a car on the lift the oil evacuation tube system is the best way to drain the oil, but for the guy in his driveway that only jacks up the front of the car, the oil drain bolt may be the best way if it is designed correctly.

But in the end, the amount of oil you leave in the pan using either of these two methods is small compared to how much dirty oil is trapped in the engine oil passages and oil cooling system so I wouldn't worry about it too much either way.

mleskovar

Including mine First, the oil drain is at the back of the pan, not on the bottom. Second, anyone DIY will stick a tube down the dipstick hole...that's the way the DIY tools work. And last, but not least, how come so many dealers have problems with incomplete removal of the oil resulting in overfill, smoking, and sometimes blown seals? (do a search and find out). The last reason is why I don't like the dealer doing my oil changes. They assume all the oil is out and put 8.5 quarts in without measuring the level. It's done with a machine/computer that adds the 'correct' amount of oil by engine type (so I was told by a dealer). I believe the "vacuum out the oil" method was developed for the same reason MB puts the oil filters up top for easy changing....it's quicker, easier, they don't need (or use) a lift, and they make more money delivering the service. Not because it's more efficient.

vinceC

The pan is designed with a depression at the bottom of the tube, as Hackman speculates. If you look at the top of the dipstick tube, the top 50mm or so is sized specifically for a fitting with "O" Rings that seal the evacuation tube to the dipstck tube. A DIYer can make a fitting (several in the MBCA have done so) or have one machined for a few bucks.

I haven't seen an M-B with the drain at the back of the pan for some time. The M103 & M104 drain is on the forward driver's side. The M112/M113 is on the pass side about mid-way back (I'm draining mine as I write this).

Most dealers that overfill do so by rounding off, i.e. 8.5 to 9, a practice found prevalent by M-B in the early 90's and condemned by them in a period service letter.

scorchie

Which is why the oil drain doesn't let all the oil drain out... imagine trying to empty your bathtub through the overflow! (Well, using a lift)

If those points don't define what is more efficient, what exactly would be more efficient?

p.s. my dealership, well, the technician I use, doesn't do things the way you suggest. Most of them in this area seem to use the dipstick to do an accurate measurement. As you seem to point out, it's more important to have the right amount of oil in the car than to get all the old oil out anyhow. The oil is going to be dirty again in 5 minutes.

-s-

mleskovar

Just noticed khaug has a CDI.....his plug probably won't be in the same place as the M112 engine, but all the same caveats apply. My M112 engine plug is on the driver side left end of the pan....even though the plug faces rear, the bottom of the hole is still at the low point.

So at best the vacuum method will remove just as much oil as draining it through the plug? If the car is level or slanted towards the exit point, if the tube is used and sealed at the top, and if the machine works properly and if operated correctly? At least with DIY vacuum you will know the last three ifs. I agree with khaug, it's too simple to have someone else do it. Also saves you time taking it somewhere and then not having to inspect what was done. Putting it up on jack stands for an oil change is dedication.

electric blue

First of all I would not take my brand new Mercedes Benz and jack up each corner placing a jack stand on each end. I dont know about you guys but I value my time and to go through thoses steps alone and then having to pull the bottom cover off undoing the oil plug replacing it back with the right amount of torque taking the car back off the jack stands then having to replace the filter and refilling the car with oil and disposing of the old oil is just plain out crazy.

Fathead

Benzel Bush in Englewood, NJ, changes the oil by vac. My service rep says they recommend it as a precaution against damaging the plug by tightening it too tight. Such damage, the rep said, requires a new oil pan.

Then again, the Stealership likes nothing more than installing new parts.

pa28pilot

This seems like a thread of knowledgeable posters, so I'm hoping someone might know this answer.

Is there a means for a technician with a vacuum system to pull an oil analysis sample without just dipping out of the waste oil container?

I ask because I just bought a CDI, and I want to do oil analysis on it. I do it for an airplane, and it seems like a good thing for a car I hope to keep a long time.

I'm already nervous about asking my dealer to pull samples, and if there's just no way to get a clean sample, I may go to the trouble of buying a vacuum system myself.

Thanks.