No, I haven't. My comment was more toward the inexperienced comments I've been reading lately on using WD-40, silicone spray, motor oil, spray grease, and the like. What a waste of effort!
25 years ago I looked at different types of rustproofing, and I was sold on Texaco Rustproof Compound L. It's a wool grease with 1-3% stearic acid, full-bodied, and stays greasy for its duration. It'll seep into crevices where protection is needed the most and remain adherent to the substrate. Other rustproofing compounds had their shortcomings.
Polygard was too waxy, and Cosmoline and sound deadener are too brittle. Over time, they'd delaminate and result in poultice or crevice corrosion.
I once heavily sprayed my undercarriage with motor oil. It lasted one month before the undercarriage was left dry. I don't expect that other such thin fluids would fare any better.
Texaco Rustproof Compound L was recommended to me by the corrosion engineers at Chrysler.
Texaco Rustproof Compound L does have its limitations. It needs to be replenished about every 2-3 years. I have one car (my girlfriend's) that I don't care about anymore. After 7 years the coating began to thin out to nothing and slough off. Hence, the need to replenish the coating.
I HATE corrosion. I spent my high school days trying to battle rust damage on my "baby". It was a losing battle. Back then I vowed to myself to spend my efforts on corrosion prevention rather than corrosion repair and the heartache of the effects of our Michigan winters. Hence my keen interest on rustproofing.
I believe there are clone compounds. Krown comes to mind. How does Amsoil HD protector compare with Texaco Rustproof Compound L? What is its condition after 4 years?