You can wash with regular car soap; it will be fine. 303 makes a cleaner product if you had tree sap, dried-on bird poop etc., that the car soap did not remove adequately. Be sure you get the 303 top protectant for a fabric top NOT vinyl. You will need to mask off the windows, body and anything else you don't want the repellent on; it comes in a spray bottle. You could also put it in a small plastic bowl and use a paint brush to apply, my approach. Here are the 303 UPC's; Fabric Protectant: 082043006164, Cleaner 082043005402, it may also come in a combo kit.