I suggest you don't degrease your engine at a self serve bay until your engine has fully cooled down. You may crack the engine block or or other extremely hot metal parts due to the rapid change in temperature.
In the self serve bays there is an option with de-greaser that you can use on your engine. Just be careful of wiring and other electronic components when you are spraying it under the hood
How much is it to wash your car?
You COULD wash the engine in the self wash, but I would recommend you not spray directly on the fuse box or other electrical connectors.
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