Evening all,
What’s best for preventing corrosion in aluminium components when using stainless steel or mild-steel fixing bolts?
I’ve heard copper grease may corrode aluminium, but not sure if this is correct? I’ve also seen Tef-gel, but it’s expensive and possibly a tad excessive for using in vehicle applications.
Duralac is usually the standard ‘go to’ for this sort of application.
Does that set hard like loctite?
I see there’s two types (yellow & green), which is the one for using on threads?
Rightly or wrongly I’ve used the yellow duralac
As far as I’m aware, green is chromate-free. The lower toxicity is more environmentally friendly.
Cheers chaps, I’ve found a bit more info (Sorry for the extremely dull topic!) 
Duralac Green is a chromate free jointing compound designed to inhibit electrolytic decomposition between dissimilar metals - often called galvanic corrosion. It is a single pack, air setting product. Duralac Green has an improved environmental footprint and exceeds standard Duralac in performance.
Duralac is ok if used where the dissimilar metals meet such as the back of the steel suspension mounts against the chassis but for bolts and threads into aluminium lotus say to use a pipe thread sealer permabond A130 or A134. I just used loctite 567. Or if it’s on a non stressed bolt like on undertrays just use corrosion block grease.