Now that everything’s hosed down, it’s time to start with the degreaser. It’s a good idea to use the engine degreaser first rather than car shampoo, as the degreaser will be able to penetrate through the layer of oil and grease in your engine bay.
Spray a liberal amount of degreaser all around your engine bay, and let it sit for a few minutes for the degreaser to work its magic. For the especially greasy bits like the starter and oil pan, give them a few more squirts to ensure that all the gunk comes off.
Agitate the degreaser a bit with the wash brush, scrubbing your engine bay with gentle motions. Using a wash brush ensures that the degreaser gets sufficiently worked up, without creating scratches on painted or plastic surfaces.
After that’s done, give it a rinse with the hose again! You should already begin to see a marked improvement at this point. However, if your engine bay hasn’t been detailed for a long time and the dirt has built up, don’t hesitate to repeat the degreasing process again.
If your engine bay is sufficiently clean after the first pass, you can proceed to finish it up with the car shampoo and wash mitt. Give it a good wipe down, using your finger to reach in to crevices that were too large for the brush. You’re now halfway done – give your engine bay the final hose-down of the day!