[truckster]

I would use it on all bolts. That way your torque readings are consistent.

I've always favored Aviation Form-A-Gasket. It's similar to Permatex #2 but comes in a brush-top can. Permatex calls it #3. Both are slow-drying, non-hardening sealants. Aside from the packaging, I'm not sure there's any difference. Permatex says #2 is approved for use in automotive as well as aviation applications, and that #3 is approved for use in aviation as well as automotive applications.

Oh, and if you use either one, clean-up is easiest with denatured alcohol.