Rubber preservative - longest lasting?

For what, like tires?

Brake fluid is one of the best rubber conditioners there is, but I don't suggest using on tires and door seals...for obvious reasons....

Products with silicone like Armor All tend to make rubber turn brown and get brittle eventually, so they don't get my vote.

I dunno. Something that cleans it well and leaves some level of UV protection without silicone would get my vote, whatever that is, or if it exists...

I've been using STP Son of a Gun, [similar to armorall]. Works okay for me, and I don't see any prob. with rubber browning.

They're tiny bellows (boots) for the carburetor. One weatherproofs the throttle position switch, the other goes over the accelerator pump shaft, probably to keep out dust and prevent gas fumes from leaking out. I'd get gas fumes inside the passenger compartment when that bellows cracked.

I checked the chemical compatibility data base at:

but the only solid it lists is paraffin, which I couldn't get to stick well (I thinned it in kerosene).

I'd like to find some kind of flexible solid coating, but vinyl paint didn't stick, and high temperature rubber glue stayed tacky forever (made the bellows stick together).

I may be (or surely am) way screwed up, but I like RuGlyde. It is nothing more than a potassium soap, with glycol, in water solution. But it seems to keep rubber in pretty good shape.

How about Cosmoline? It's a paraffin base, with a solvent added for easy application and some strong reducing agents. Works well on metal parts but the military uses it on rubber as well.

--scott

The problem is that there isn't just one kind of rubber. There are lots of things... silicones, natural rubbers, urethanes, neoprenes, etc. which are all referred to as "rubber" but which have totally different chemistry. This means having one product that works on all of them is sort of difficult.

For years I liked the BMW "Gummiphledge" paste for door and window seals, but they have stopped making it.

On natural rubbers, methyl acetate will take the gunk off the surface and keep it nice and soft. But it'll wreck urethanes.

--scott