I mainly do residential pw but have decided to venture into fleet/car washing. I actualy landed a good size car lot around here-350 cars and a solid waste company-30 trucks. I've only used sodium metasilicate mixed with bleach for house washing. Called up my local chem. distributor and asked if sodium hydroxide would be ok to use for these applications. He told me that it was to harsh and I could get away using potassium hydroxide. Are either one of these alright to use for this? I'm woried the sodium met. won't be strong enough for the trucks. Pros-cons for these?