We've not used the Rubber Shield, but have used 303 for many years. We've only had this rig for a little over a year, but used it on the motorhomes with good results. It seems to do a great job at UV protection. I sold it for 10 years at the hot rod shop and never had a bottle returned. We use it on just about everything. I really like it on the car dash, as it repels dust and isn't greasy like a lot of the other stuff is.