As threadlocker goes, I got mine from Lowes I think, it's Loctite Tite'n and it's blue.

I've heard elsewhere that you should never use threadlocker on prop bolts, and I would tend to agree.

When my engine threw the APC prop and spinner, the recommended solution was to just get rid of the spinner and turn the rubber starter cone around. This worked fine for me until I got a decent spinner. No loctite or special nuts requred...