Stripped oil drain plug...
 

Everybody's done it at least once, right (I need some reassuring)? So I go to change my oil this morning, and I put a 12 point 13mm socket on without thinking. Felt that awful feeling of soft metal bending. Tried a six point 13mm to no avail. Hammered on a 1/2" six pointer, no luck. Hammered on a 12 point 12mm, just kept making it worse. Vise grips, nothing. Any suggestions before I go to sears and pick up a set of those sockets that eat into the metal (and a new drain plug)? I could've sworn that I made sure not to overtorque it last time I changed the oil, but I suppose that I did. I also made the mistake of doing this with the engine hot, so the head of the bolt was a bit softer than it should've been. Never again. Don't have a mig welder, or else I'd stick a nut right onto it.

I'd go the extractor route, I've had to break down and get a set of them and they're pretty darn effective. You're lucky though if it's just your drain plug. I've stripped the threads on the oil pan before and had to replace both the pan and the plug. Not near as trivial a fix!

Since it's Sunday, this tip probably won't be effective, but:

If you can locate a small bit of dry ice:

Heat the entire area around the drain plug with a propane torch. You don't need it too hot. Just get it warmed up pretty well.

Then, with a gloved hand, press a piece of dry ice on the head of the plug and hold it there for about 7-8 minutes. If the piece evaporates, then get another piece. Press firmly against the plug (gloves!!!). The dry ice will "scream" as it evaporates. Don't let the ice touch the oil pan.

The 7-8 minutes is just a guess. The head of the plug should be so cold that it forms frost on it from the humidity in the air (well below 32°F.)

Hopefully the oil pan remained above 100°F.

With a 100°F. differential in temperature, the plug should come right out.

I stripped the head off my 260E's pan plug. Tried everthinhg to grab & twist. I even drilled a hole into the middle to use an extractor on it. Nothing worked. I had visions of cracking the oil pan. Finally (after buying a replacement), I took a small sharp chisel and hit the edge of the plug. Hit it tangentially in several different places. Hard to say it, but easy to do. One spot curled up quite a chip. The plug unscrewed abut a minimicromillimeter (technical talk) and then it was loose. It just came out very nicely and acted all innocent. What a *****.

Now I suck the oil ot through the dipstick tube. Suckers

BTW, hot engine oil is nowhere near hot enough to soften that steel plug.

Hi

I had the exact same problem just last month. The plug is indeed very soft. Finally the shop had to weld a 17 mm bolt onto the plug to get the grip needed. I'm buying a oil extractor device too.

Oreo

I just had that exact same thing happen to me just a week ago. I had to buy one of those bolt extractor set for $19 at Harbor Freight. Quite effective. Use the smallest one that would fit ovet the stripped bolt. Pound it with a small hammer. It came right off. Good luck.

Stripped Oil Drain Plug
 

A fairly easy solution for me was to take a flat file and file the rounded plug head on two sides to the point that a 1/2" open end wrench would fit it.
Came right out. I liked it so much I filed it down to a four-sided head to fit the 1/2" wrench.
Al

The problem is that the bolt is very long, and it is steel threaded into aluminum (corrodes). If you put grease or antiseize on the threads, this will not happen.

Better yet, I got a Fumato valve. No more drain plugs for me.

Scratch the drain plug and get a TopSider, does it all from the top the same as the dealer does. I've been using a TopSider oil extraction unit for the last 10 years for my cars and boat. They are available from any marine store for
about $39.00. Works great, can do an oil and filter change on the 300SD
in about 20 minutes. Here's 2 links to oil changes on your mercedes
with photos.
http://www.peachparts.com/Wikka/OilFilter1
http://www.peachparts.com/Wikka/OilFilter2

Mine had not a spot of corrosion. The long steel threads into the aluminum pan were beautiful. Once that plug moved the tiniest bit, the plug just spun out with fingertips.

the old screwdriver way
 

the flat screwdriver will do
I had the same problem with 1988 300E and I solved it this way :sun_smile

Get a Fumoto valve
 

When you get the plug out replace it with a Fumoto valve.
http://www.fumotovalve.com/