Use real coke, and if you can heat it. i mean really heat it till it boils for as lonmg as you can
it will unseize pretty much anything.
this coming from a person who has about 50 cans of plusgas in the cupboard and prefers to use coke !
Cheap coke for about 5 hours, after boiling water directly on the adjuster ring, after leverage + c-spanner = no success.... It seemed promising at the beginnig, as a lot of gunk was floating on the water after an hour.
It really seems like I have to use agressive methods to make it work.. I'll try diesel next time, but still afraid of melting down the protective zinc coating. If that doesn't work, say hello to battery acid.
Edit: repeated the procedure using hammer and flatheaded screwdriver, but still seized..
a mate of mine had this on his tein coilovers. he had to use a junior hacksaw on the locking collars and before cutting down through the threads smack a small chisel in the slot you made to crack the collar. its last resort but easyer to sourse new lock rings and much better than wrecking your coilovers completley.
When I did a set of coilovers last that were stuck I froze them overnight then dumped boiling water over the rings that was after soaking them in coke for a day. This method does take 2 days with your car in the air tho. And when freezing them you have to leave them in your freezer for about 12 hours to get them proper frozen.
Mine is unseized aswell. Took it to a suspension place, and they unseized it for me. They used heat aswell. They did it for me for 10 pounds. Gave it to the shop, they gave them back 3 hours later. So this was my method.