Ethan's point about avoiding a strong spray is good. The really high pressure spray can knock some things loose..ie..connections, etc.
I use the engine cleaner spray setting, followed by the soft, spot free rinse.
Needless to say, you don't want to do this when the engine is red hot. Fortunately for me, I live just yards from a self-serve car wash.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.