I use a brown grease specified for aircraft doors etc, that I bought cheap at €3 for a canister of 1 kilo, in a metalware store.
I tension the bolts, subsequent days I check and tension again if needed, and usually, after that no further attention needed.
Since my chainring is now bolted with default metric bolts and nuts, there isn't any risk of damaging thread anymore, so I just tension as hard as I can with standard length key 17.
I never used threadlock.
The dealer of my current bike did (the red loctite), for the bolt on cog on the IS disc mount. The bolts were way too short, about halve of what the specs of the hub flange recommended. The longer replacement bolts didn't turn in well, after trying 1 I decided to not take the risk, and instead first tap out the 6 flange holes. That worked, and didn't cause further problems, now being 4 years ago.
The benefit of a thread locker appears to me as making sure the mount is fixed directly, post-leaving the shop, as to not require customers to check the bolts in subsequent days.
In my case, that isn't a problem, since I have the tools and do it myself.