Copper grease?

[winjohn]

Probably teaching how to suck eggs but the reason for grease on stems and seatposts is to put a layer between the aluminium and steel since in contact they create a galvanic reaction which causes corrosion and leads to the stuck stem or seatpost scenario that most of us are unfortunately familiar with when renovating old bikes (although never with our own carefully maintained bikes of course). Copper and aluminium also create galvanic reactions together.

Steel on steel, no galvanic reaction but you just need something to keep the water out to prevent rust.

Ordinary grease will do both these jobs adequately on a bike.

 

[Imlach]

You can pry the bike fake tan from my cold, dead hands.

 

[dyna-ti]

I use white lithium grease, and I slap it on with a paintbrush in places like a bottom bracket. Slather it on the threads on the frame, and slather more on the threads on the bottom bracket, and then slather on some more just to be safe.

Get plenty on your seatpost too, and check that at least once a year. On the headtube helps the headset cups go in, and more importantrly, come out again.

In fact coat everything in grease. And while lithium is good, normal Castrol 'brown' grease is just as good. Copaslip isnt, its more a specialist type of stuff and there are places that you should never apply it(Aluminum for example), so with that in mind stick to a grease that can be put on anything.