The question we often get is how do i clean my dandy the answer is easy but the work can be hard if it hasn't been done for a long time,the most used method is to clean the pvc inside and out with ciff cream cleaner,i don't wet the pvc first just use the ciff on a wet cloth small areas at a time,then when one section has been completed i rinse it off.
With elbow grease its surprising how clean you can get them when its all been cleaned rinsed and dried a coat of mr sheen and a good buffing will make it look good and help clean the dirt off next time. The inside of the roof needs a really good polish as this helps it slide over the roof bars,more people are now using a silicone spray that dries and leaves a very slippery surface,i intend to try this myself.
There are other cleaning products that would do the job but care must be taken you don't use one that takes the surface off the pvc ,some off these cleaners may be ok once if there is dirt you cant remove but use with caution and only once.

A great example of how clean a Dandy will scrub up with a little time and effort.

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