which threadlock to use

Ok I have a 90 degree oil adaptor for spin on oil filter.

I need to tighten a banjo bolt through it to hold it onto the engine(perkins prima)

the adaptor is ally and so is what it bolts to, the torque will be no more than 25ftlbs but these have a habbit of working loose.

So which grade of threadlock to use?

Any ideas?