Read carefully the labels on the purple degreasers as a class. They are caustic, and should not be used to degrease aluminum parts. The labels clearly state that warning. There are a lot of aluminum bits under the 928. Use solvent-based cleaners if you can. You may decide to use caustic degreaser products because they work so well. Know that they damage the aluminum, causing a dark hydroxide degradation product. Unlike the natural aluminum oxide layer that forms in the presence of air and moisture, the hydroxide layer is not "self-protecting" for the underlying aluminum. The reaction continues well past mere surface discoloration. It -may- be OK in advance of a thorough steam cleaning, followed by a water rinse. You need to remove every bit of the caustic cleaner, and that can be a chore. It finds its way into corners and cavities, making total removal unlikely. Know that caustic cleaning products in general are banned for aircraft cleaning, including common and seemingly benign products like regular Simple Green.

 

Uh, 150PSI of 360F steam is fatal if inhaled for even a few seconds. One or two puffs will melt lung tissue almost immediately. It will also peel skin off nearly instantly. Lets not get anyone hurt or killed trying to clean a car. I'm going on record NOT to do this. For people that have never been around high pressure steam, just -- don't.

 

6 pack of beer, elbow grease, a creeper , degreaser , glasses and the car up on the lift. Also get some angled attachments for your brand of pressure washer.

i never bothered with steam at all.

above all FIX what is causing the grease and dirt (oil pan gasket...hoses...bad CV boots etc) Once it is FIXED, keeping it clean isnt that hard.