Penetrating oil,any recommendations?

[Partridge]

Another vote for Plusgas. It make taking a wing off of a 1998 Rover a lot easier*. Unless you want a "bad high" make sure you leave the garage door open though, it's pretty potent...

[PhillipM]

PlusGas, Ferrosol, (supercrack from ecp is pretty good too if you're in a rush for something)  or if you have it and can be arsed to mess around, acetone or IPA mixed with the thinnest shock absorber oil your local bike shop sells will help immensely on anything you can't get heat on.

For jobs where that rusted nut completely stuck and never, ever coming off and you're now completely fucked as you can't get any tools in there bar a spanner - then take the acetone from the above step, dissolve about 5g of citric acid in 100ml of it, and apply it every hour or so for a day or two, it'll wick right down through the threads and the citric will dissolve the rusted bonds.
 Then use the acetone/oil mix a couple of times before trying to release it.

It's a bit of a faff but I've had siezed on, rounded off nuts that I've unscrewed just with a pair of needle nose pliers after that.

Blowlamps are still more fun though. Combine it with the SuperCrack freezing stuff from ECP for the full effect.

[fordperv]

Double tt has got me out the shit a few times

[tommotech]

If you can get hold of Würth stuff their Rostoff Ice is excellent. If not plusgas is a close second.

 

If neither work heat, with an induction coil (now starting to become affordable), blow torch or gas axe. If heat is not an option then a good soak with brake fluid usually works with hammering the bolt / nut to shock the threads into submission.

 

When I was young my Grandad used to use Horse Liniment oil, the place used to smell awful but it cleared your nasal passages out!