I just keep the engine running, and make sure not to use direct blasts of water near major engine electrical (MAF, alternator, back of headlights, coilpack area)

Spray down liberally with Simple green or equivalent, rinse off, and use dressing of choice. I use Adam's in and out spray

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards