Funny i saw this, i just did mine today. Best thing to clean a nasty greasy engine with is....believe it or not Easy Off oven cleaner. Don't get the fume free stuff....it aint worth a crap. Just spray it on and really soak the heck out of it, wait about 20 mins...then rinse off. This stuff will turn your aluminum a dark gray and leaves some oxidation behind. I go back over the large areas with some soapy water and a red scotchbrite..just to loosen up the oxidation a little.
The easy off kind of etches the aluminum and makes the paint stick like crazy. Really heavy stuff might need a brush taken too, but this stuff pretty much takes it all off without any scrubbing.
