Not so the foam cleaner of K2R. It can be sprayed well targeted and liable min. 15 minutes in place to run ohnen. The Cleaner is extremely economical - one should take less rather than too much, otherwise you have to wipe a long time to remove all the streaks.
The dirt from the disc (soot, tar, resin splashes) goes under the proposed soaking (min. 10 min.) Thoroughly.
The three-pack is very low and will probably suffice for several years in economical dosage.
A strong buy recommendation!
