Anything Stronger than Wheel Brightener.

agreed. buster is unstoppable.

 

I am a big fan of PB's Spray and Rinse for highly neglected rims. I have yet to find anything that stuff won
't budge I have tried P21s wheel gel and CG's sticky wheel gel which btw isn't sticky or gel like in any manor and a let down compared to the previous two mentioned. One caution with PB's SnR is it uses floric acid which can be nasty stuff. I believe there was a dicussion about floric acid in the last few months on the board here.

 

This stuff works pretty decent:
Bromoco Wheel Cleaning and Restoration Liquid

 

I agree that it isn't a gel as such, but if you watch it after you spray it on, it runs like molasses. Sure it runs somewhat, but a good portion stays on the wheel. I think it cleans easily as well as P21S.