Extrutech Panels Stained

Guys,
I have extrutech panels we had them installed at our full-service a year ago. We noticed near the exit of the tunnel we have smog markets from the exhaust (where we start the car) that are staining the extrutech panels. We have tried scrubbing it out...no luck. Based on your experience what is the best thing to do to have it looking clean again?

Klean Wall should take it right off. I get stains from diesels on the walls and it comes off very easily with it.

I use Muratic acid to clean my Extrutech. Its safer than most acid wall cleaners and works quite well for us.

I use a mixed acid...10% hydrofluoric and 6% sulfuric. Muratic is stronger than the mix I use. Be very careful. See previous posts on HF.

I get mine from a small chemical company than mixes products for truck washes.
They use 2 step cleaning processes a lot because of the amount of aluminum on rigs and hf HF is a great aluminum brightner and rust remover.

Always have calgonate tube available if you use HF and limit access to the product to only those trained and equipped to use it.