I just picked up a 1997 F150 4x4 with no rust that I plan to keep for a bit. Instead of paying for Rustcheck, I've been told a similar treatment can be done with equal mixture of WD40 and auto trans. fluid applied similar to pro jobs but with a garden sprayer. Anyone used this technique or something similar?

 

Nope. But I can imagine it'd make a big mess. Lol!

 

I'm sure who recommended that particular concoction to you, but I've never heard of it before. WD-40 does have some decent corrosion inhibitors in it and flows quite nicely into tight places. ATF has no corrosion inhibitors in it and has has a higher viscosity. I'm not sure what its part in the brew is.

My personal opinion is that WD-40 alone might do something, but the ATF is pretty useless. I'd also add that anything that you apply is going to create quite a mess. Think about it carefully before you start spraying. Good luck.