I have become quite a big fan of: Menzerna Power Lock Polymer Paint Sealant. I never heard of it before joining this forum. It works great. I recently tired it on my alloy wheels and was blown away after 600 kms of hard brake use... I went to the local selfservice car wash place (high pressure wands/jets) and all the brake dust came off of the wheels. No cleaner was needed. I really am sold on Mez.
What I also like about using Mez is that it leave the paint really smooth and silky to the touch. I like to put on a few coats and let the car bake/seal out in the sunlight. This seems to "lock" the sealant onto the paint for weeks to come.
Dackel