Originally Posted by radiofrequency
To reply, I use Sonax Full Effect about every 4 washes or whenever I remove the wheels completely for a full detail. (Or whenever I swap over to winter wheels from summer wheels). I mention this because you use this cleaner when your wheels are in bad shape - if you look through the detailing forum, it's the stuff that goes on green then turns red on the wheels when it reacts with the brake dust. To me, and this is IMHO; the Sonax P21S Gel is gentler, also the gel consistency ensures that it does not run off the wheel faster than you are able to agitate the cleaner. So, I use the Sonax P21S Gel in between the more serious cleaning, it does work well, and I typically buy all my supplies, in bulk, when the detailing stores have their 15% off sales.
Interesting! What you mention about the P21 is the same observation that I have made as well; very gentle but yet effective and the gel is great to work with. I did not know that the Sonax was more harsh. Thanks for sharing!