After the degreasing comes the full cleaning. If you have a car wash or car shampoo fluid, this is the best time to use it. Spray down the entire underside with your cleaner, making sure to hit all the nooks and crannies.
Now, blast the heck out of your undercarriage with either a pressurized garden hose or a power washer. If your car is raised on jacks or a curb, you should be able to target all sides. Muddy water, degreased residue, and grime will likely splatter all over the place. This is normal.
You can stop once your spray ejects only clear water. Let the water drip off a bit, and use a flashlight to check for any remaining residue. Use your degreaser and brush to eliminate any, then give it a final blast with the hose.
Finally, you have the option to add a protective coat to your undercarriage, as it is one of the top ways to protect your car from rust. These protectants usually come as a spray, such as the Chemical Guys Bare Bones Shine Spray.
If you store your car in a garage where it’s slow to dry, you may also want to give your entire car a quick dry with a hand cloth or old towel.
After all is said and done, you can rest easy knowing that your car’s undercarriage is squeaky clean and ready for the road.