To clean, simply mist the engine bay with your spray, let it sit for a few minutes, then rinse. If your engine bay is especially dirty, you can agitate the grime with a rag, or you can even use a ...
Vehicle repairs and maintenance tasks don't always have to be done in the shop. You can easily do these in your own garage.
Washing your car can be important during winter to deal with snow and road salt, but it's not wise to get it cleaned when it's too cold outside.