Went to do a routine oil change this weekend just gone but could not get the sump plug undone for the life of me. I have doused it in WD-40 and given it a whack with a hammer but it is absolutely welded to the sump. The only thing I managed to do was round out the star socket of the plug. It literally just corroded as I turned so not sure what to do now. My guess is the garage that changed the oil last tightened it way too tight or it has become corroded over the year, either way it ain't budging. Any suggestions on where to go from here? I'm thinking I will probably take it to a garage and see if they have any tools that may get the thing out. Can anyone recommend anywhere to go in Bristol/Swindon?

AFAIK it's not meant to be a star socket, but a hexagon one. Been a while since I did it, but I think it's an 8mm one. Sometimes with grime in the hole it can seem like the size meant to fit in won't, but it needs a bit of a tap/clean out. If you use too small a tool then that would easily cause rounding out. See if you can get a bigger one in, or fit something like a torx fitting in. Maybe try mole grips.

Something else you could try is a blow torch (or high wattage soldering iron to heat it) and/or freeze spray prior to attempting to loosen

If an oil change is all you want to do you could resort to using a pela type pump. E.g. http://www.screwfix.com/p/laser-oil-fluid-extractor/21663

When you tighten it yourself the best bet is to use a torque wrench to ensure it is done tight enough, yet not overtightened.

If it was me...

...I'd go and purchase a replacement sump plug first ready for the worst, then use mole grips and plenty of dislodging stuff - no matter what you end up doing with that sump plug it'll not be fit for putting back in.

If it was me...

...I'd go and purchase a replacement sump plug first ready for the worst, then use mole grips and plenty of dislodging stuff - no matter what you end up doing with that sump plug it'll not be fit for putting back in.

Exactly what this member says, adding go back to the garage that did your oil change, and ask them to just slacken it off for you.

Further to giandougl's post:

I'd be prepared to take it back to the garage that did the change last just in case - if they've managed to strip the threads on the sump by over-torquing then I would have thought you would be in a position to demand they foot the bill for remedying it.

I'd be careful with telling the garage you attempted to remove it though. I'm sure the garage would like nothing more than to blame an "incompetent diy'er" (their likely words), and avoid having to pay anything out.

I'd be careful with telling the garage you attempted to remove it though. I'm sure the garage would like nothing more than to blame an "incompetent diy'er" (their likely words), and avoid having to pay anything out.

My thoughts exactly. I've ordered a new sump plug and i'll check again to see what the socket is. I was using a T50 torx fitting to undo it as this seemed to be correct but I may have messed up and used one size too small or something. When the new plug comes I should be able to see exactly what fitting it is before trying again. Hopefully there will be something left of it to play with! If it doesn't feel like it's going to move i'll take it to the garage and hopefully they will be able to get it out! There must be a few tricks of the trade they can try which hopefully won't end up in replacing the sump.

You sure your at the sump plug? Not the gbox plug?

Theres a fancy oil pump you can buy that sucks the oil out from the filler neck i think

Supposedly a lot of dealers use this way

You sure your at the sump plug? Not the gbox plug?

Theres a fancy oil pump you can buy that sucks the oil out from the filler neck i think

Supposedly a lot of dealers use this way

Yea, pretty sure i'm at the sump plug I guess if all else fails an oil pump will have to do, but always thought it's better to let it drain from the sump if possible.

I've learnt the hard way to always, always clean out socket-head bolts (torx, allen, spline) before applying force, and if in doubt, tap the tool gently in to ensure it's seated. Good luck.

I'm fairly sure it isn't a torx on the sump plug?

Nope - it's a hex I think...

6mm comes to mind..

6mm comes to mind..

I'll be sure to have a good look with a torch before having another go. Hopefully the torx socket i was using was not ideal and i can still get a good seal with a hex socket if you are correct.Thanks for the comments.

You sure your at the sump plug? Not the gbox plug?

Theres a fancy oil pump you can buy that sucks the oil out from the filler neck i think

Supposedly a lot of dealers use this way

I was very tempted with one of these when I serviced mine last month.

http://www.ebay.co.uk/itm/4-LITRE-OIL-FLUID-EXTRACTOR-PUMP-MARINE-CAR-PLANT-VAN-/300586123572?pt=LH_DefaultDomain_3&hash=item45fc544134#ht_483wt_1792

Regardless what the garage thinks you just want the sump plug loosen/replaced.

Have it so they can lift your car up onto their ramp and, can go straight to trying to remove it, with their equipment.

Ok, so it was relatively simple in the end, you guys were right, it's an 8mm Hex socket fot the mpi sump plug, so using the correct fitting hammered in to make sure it still gripped despite the rounding I was able to get the thing undone. So, oil change done, thanks again for the help.

Ahh, 8mm.. Was nearly right!

I was very tempted with one of these when I serviced mine last month.

http://www.ebay.co.uk/itm/4-LITRE-OIL-FLUID-EXTRACTOR-PUMP-MARINE-CAR-PLANT-VAN-/300586123572?pt=LH_DefaultDomain_3&hash=item45fc544134#ht_483wt_1792

I've used a vacuum pump (from Screwfix) to extract the oil during my last 3 services, it works a treat. Apparently Mercedes use this method quite a lot.

Edited 10 October, 201114 yr by Chorlton