I am a limousine driver. My outdoor limousine park (I don't have a 30 foot garage) is in Los Angeles. tree sap. A car wash will not turn a brown top back to black. I use Ragg Top once a month or two. ) every week or more, but I can't clean the top every week (remember, it's a 28ft sedan). If you use this product once a month, the black top will turn black again.