exactly what i use....i spray engine down with pre-mixed sutff in a hand sprayer bottle....let it soak...scrub any spots i know are dirty...then i connect my pressure washer to a bottle it can suck cleaning solution from....fill it with concentrated sg and put on the soak tip...spray engines some more. After a couple mins (before it starts drying) I put on the general purpose tip and disconnect the bottle and rise that shit off. My washer says its 3000psi at highest rating, general tip is lowest it can go around 1000ish psi.
BTW, SG has a purple version...supposed to be even stronger...i use it when washing my quads...works good too.