I use Castrol General purpose cleaner in the purple bottle. I warm the engine up (Just a little), give it a quick rinse, then spray on the degreaser (Cut 50/50) makes sure you don't get any on the paint (I Ussualy wet the hole nose of the car to be safe). Rinse off. Wait for it to dry and use what ever you like for an armourall type product. I detailed for 10 years and it always worked well for me.
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