i found some exterior house siding cleaner at a garage sale,cant remember its name but you attached your hose (from house) to it and it sprayed threw the cleaners nozzle. any how it worked great for me,mine had green stuff from under the pine trees where she sat till i got her.I did have to put some in a scrub bucket with a scrub brush on bad spots .The sides cleaned fairly easy & after that i bought 2 gal. vinegar & wiped it down with that .Then a clean water rinse with the hose to get all chemicals off.The paint ( mines a original 78) is faded a bit & dull .I imagine wax wouldn't hurt .Eventually when i can find the right color for the middle color . My 78 has got a brown strip on top & bottom & is a light beige in the center. A good tip though a bit spendy is HENRY'S rubber roofing .Its like $ 95.00 a 5 gal. bucket .It works great on sealing the roof (lasts 7 years) & makes the roof look like new,( you roll it on with a paint roller).Good Luck.