Car polish removes them easily, stopping them completely is difficult but having a clean and polished roof helps.
------------- Bill
For a licence dated 1997 or later you must add together the plated max weight of the caravan and trailer, if the total is 3500 or less you can tow it. You may even tow a caravan with a MAM greater than the cars unladen mass the restriction was removed in 2013
The black streaks are from atmospheric pollution and other airborne debris that settles out on the roof and then washes down the front, back and sides. As above if you keep the roof clean you will minimise the streaks. A good quality polish will assist in keeping the roof clean and make it easy to wash down.
------------- 'A sure cure for sea-sickness is to sit under a tree'
We got rid of black streaks - eventually by using Muck off. The streaks were only just visible but I knew they were there so next wash I sent DH up with the squirty bottle and a cloth and they are gone.
I trawled the internet for the best wash and wax and found one product mentioned on several websites. We now use Meguiars Ultimate Wash & Wax which has carnauba wax and synthetic polymers.
We do still get black streaks but they just wash off with the next application of Meguiars. We still have the muck off on standby though
I know it is expensive but we have used ours all summer and still have half a bottle left for next year.
I know this may sound a bit strange but it does work, sometime ago someone suggested to actually paint the window rubbers with an proper black rubber paint, so no more black streaks i did it once on a small VW and i must admit it worked a treat.
A friend of mine has a caravan and his is always spotless, which made me ask how he keeps it so clean. He says he uses a 50/50 mix of Tcut and Turtle wax, then finishes off with Fenwicks spray cleaner which puts a film over the surface. Any marks which subsequently appear will wash off just with a cloth or a hose. I have a Renault T35d campervan and must admit I haven't tried it yet but definately will in the spring.
Aldi...On Sunday(yesterday) Black Streak Remover...and...Caravan cleaner....both at 2.99.each. I know that the cabuba car wash and wax is absolutely excellent at cleaning the roof of our van...so as of yet we have suffered no streaking...( I will catch one for u if I see 1 run by me!) so would deffo think that this will be good also.
I'm conducted a very scientific??? test this winter on this very subject.
I have gone over all the sides, back and front of the 'van with "Greased Lightning", that product advertised on TV as preventing road tar and paint from sticking to treated surfaces.
The 'vans on the drive (probably until Spring) and if any Black streaks appear I will see if they are removed with GL as it does on the TV.
------------- How come when some people visit the fountain of knowledge, they only gargle!!!
Autoglym caravan & motorhome cleaner will get the black streaks out every time and when you has washed it it will keep the muck and black sreaks away longer.
I cleaned my van with Mer this weekend. it removed black streaks with ease.
after reading this thread earlier I also got up on the roof and polished that to showroom condition too. I'll let you know if keeping the roof clean minimised the risk of streaks forming as claimed.
I bought the Mer from my local Costco (far cheaper than anywhere else) - it is by far the best car polish I have used and not as "sticky" as some others i've used and a doddle to buff up
------------- It's only an expensive hobby when it's parked on your Drive....use it, love it , live it.