Hi, apparently a 50/50 mix of acetone and ATF is way better than WD40 and all the other penetrants - that's what I read on a US forum, gotta be worth a try.

Hugh
Very likely true. Acetone will evaporate leaving a oily residue. There are many better 'penetrative' materials available than WD40.

https://www.youtube.com/watch?v=xUEob2oAKVs
Forgive the somewhat annoying delivery!

I use plusgas, I think both the tins I have must be 20 yrs old, you can see the difference between wd40 and plusgas, the plusgas absorbs into the threads straight away.
I’ve got 5 Ltr s of wurth penetrating solution to try when I get round to it,

WD40 was developed as a water dispersant but it was found that it also acts as a lubricant amongst other things. Basically it's a Jack of all trades, master of none in a can. Plus Gas is formulated specifically for freeing seized bolts but I must admit, ATF on it's own works pretty well too.

Hmmm, Plus Gas. Remember the smell.

Can't get it here. Fortunately, none of my fastenings have needed it, due to lack of salt.