I bought a nearly pristine 1-owner 97 F250 4 door 2wd PSD a few months ago. The engine just has the typical dust on it as it has never been washed. I typically wash engines in my cars very briefly at a car wash just to keep them clean like the rest of the car. I've never had a problem doing this but is it a good idea for my PSD? If so, are there any areas I should avoid other than the real obvious electrical equipment under the hood?