I use a degreaser (Gunk) on a slightly warm engine about twice a year. Then I use the garden hose with the sprayer after it sits for about two minutes. I do everything. The top of the fusebox, plastic air cleaner cover - everything. Then I keep the hood open for about an hour in the sun before starting it. Never had any trouble and my 97 Subaru engine compartment looks like new.

to add, not on a hot engine. only because a cold engine will not produce steam. which if in the wrong places can cause serious issues.

i don't use a car wash. i buy cheap citrus cleaner in a spray bottle. couple of brushes. garden hose on low. section at a time to wash and rinse.

avoid all electrical connectors/components. ensure no water gets in the air box.

should be fine.

sounds like you got a rusty coolant leak too .

Spraying water on an engine is not a terrific idea, but if you do it from below, it should be fine. BTW, the mud might have something to do with why you have to check your oil once per week.

I wrap all electrical components in plastic, then use a cleaner/degreaser and soft bristle brush to agitate it in, then rinse with a gentile stream of water. Alternator, distributor, fuse boxes, connections, everything gets covered.

Keep the water away from the ignition coils, spark plug wires, plug wells, and any electrical connectors.

There's this rust colored mud all over, I have to check my oil once a week and its gets all over my hands when I'm under there. Is it safe to spray it down with low pressure when I go to the carwash?

if it helps any I have a mitsubishi montero

and by the way, where did the mud come from? I've had a few issues with my vehicle in the last year or so, I dont know what could have caused it exactly..