Can someone confirm, with any certainty, whether rockshox reverb hydrolic fluid is regular mineral oil (as used in shimano hydraulic brakes?

Nope, it’s 2.5wt suspension oil.

No idea if ‘mineral oil’ would work, I can’t see why not, but you’d be risking the post for the sake of a fiver for a bottle that will last a lifetime.

On he contrary. I need oil to bleed my brakes, my halfords are out :/

Citreon LHM mineral oil from your local car shop.

Definitely don’t mix. The two aren’t interchangeable. As already stated LHM is a good alternative and you shouldn’t struggle to find someone who stocks it in the local area.

We also stock both if you can wait for 24hr delivery.

Fluids