i got mine cleaned by using "purple power", its a REAL degreaser. the crap that comes in a spray can is poop. all that shit does is make you nautious from the fumes. the purple power, some brushes, and rags to dry it with were all it took...and some patience and bruised knuckles

note: i thought my block was bare aluminum, but its not, its just silver powder coated or paint or something...but im sure you already knew that

...and uh that purple power stuff is only $4 a gallon! its alot like simple green on steriods

the trick is to dry the sucker before water spots have a chance to appear...and ALWAYS wash the engine when its COLD.
you can get it at wal-mart (white trash central-lol)