Socket size needed?

And where I can get new washer?

If I remember correctly its a 17 or 19mm - the washers can be got anywhere.

Just take the one off thats on it at the moment, clean it up and hold it over the gas hob or a blow torch flame until it goes a cherry red colour (don't let it go orange). Have two pairs of pliers so you can get the bit heated up under where you held it the first time.

Then, just let it cool naturally, now take some very fine sandpaper or a file and on a flat surface run the washer on each face across the paper once one way firmly. Then turn the washer 90 and run it across again.

This will cross hatch the washer and create a fine copper grooves which will help when the washer is squeezed up against the sump.

You can also if you want, put a very slight smear of hylomar or other gasket jointing compound onto the washer to create a good seal, I don't I just anneal it from time to time.

Ok, thanks.

I just wanted to make sure it wasn't a stupid size (like wheel nuts) and that I can fix my mate's brother's oil leak. Apparently he's not the least bit practical, so I figured I'd earn myself a couple of quid...

So RED hotting and cross hatching it saves the "expense" (if you can call it that) of getting a new one?

Good.

aye... copper prices these days!

S'aright if you've got a load of old-ish pennies.

But you do need A LOAD of them to make it worthwhile...

What size is the washer?

I'd rather have one than take it off, only to find it's knackered and I'll need another one.