That sort of white synthetic 'buttery' grease that you always used to find on slide rails in CD mechs, cassette mechs etc, was called "Floil" - at least the one that Sony supplied was. I had a tube of it for years as only a tiny amount is used. Sadly, it finally ran out last year. I've no idea whether you can still readily get it. I don't find that there's a lot of call for it now, as not many CD lasers are still changed, and many DVD lasers are replaced as a pre-aligned and greased deck, or sub chassis. Where I do need to lube slide rods these days, I use a light synthetic machine oil called "CMO" (Clear Machine Oil) from Electrolube. Very good lubricant, with excellent long term 'cling' properties to very shiny items, like chrome plated slide rods.
Arfa