How to clean factory alloy wheels on my RT?

[009jim]

I have factory alloy wheels on my camhead RT. They appear to be a light grey painted finish. I've been cleaning the wheels starting with slightly soapy water which removed dust and grime. Then I used a rag lightly dampened with some turpentine to easily remove tar spots. Then things got more difficult. I still have some "stains" which I was able to have limited success with a conventional auto polish. Anybody got ideas to remove the remaining marks / stains? I suspect these have resulted from bugs gizzards that were left on the surface for too long.

[Rinkydink]

I have used WD-40 on the tough spots. 
Disclaimer…I don’t know if WD-40 is harmful to your wheel finish or not. I just used it for removing old wheel weight residue. Test first.