[Xlot]

Some locals use kerosene to wash their engines - on a cold engine, to avoid creating an ignitable mixture. Spray liberally with kerosene, then wash off with a hose.

Personally, I go with running the car until engine has warmed up - then foam with some ph-neutral degreaser, and rinse off with a pressure washer on low pressure. The pH neutral is important - aluminium blocks can corrode with hydroxide-based cleaners, which makes them look ugly, and can cause long-term issues. I use some citrus degreaser stuff, followed by "CT truck wash" - both are ph-neutral (and also safe for anodized wheels).

I prefer the warm-engine version as it helps dry things out to reduce the risk of corrosion in electrical connectors etc.