Which grease

[Lyra]

Had an unintentional encounter with the dock - had to remove the transom ladder to fix it. The bolts also have to be replaced (already got new).
When I removed the bolts the threads were clean but I noticed some type of grease at the end of all the bolts - I think the threaded insert on the boat is aluminum. It is light gray and the texture and consistency resembles that of electronic heat compound.
Any suggestion what grease, if any, I should put on the bolts when installing back.

[Yngmar]

Sounds like lithium grease. Starts white, but gets grey or light brown with age.

Any waterproof grease will do, I typically use silicone grease as it's cheap and has a very wide range of uses on boats, plus it's clear so less messy if you get it on your clothes. If you're short on space, get some Superlube, which is fancy silicone grease with PTFE mixed in, giving it an even wider range of uses, but at higher cost. Winch/furler grease will also do and is typically silicone or calcium based.

[Lyra]

Thanks - you reminded me that I have grease for the winches. Will use it.