I think UV(Light) is the greatest cause of plastic degradation.
Look at the Plastic side of the bike that is stored leaning toward the sun.
Usually the only plastic item that still looks less "Chalked-Up",but still is on the sun side is to a lesser degree is the tank. So Fuel oil must be some sort of Saviour.
Frostype400"s post about not stressing a tank out when mounting it, makes more sense than anything I have heard for a while.
And Geoff,,,,
After a couple of weeks of having fuel in it, over a 24 hour period the sides of the tank became concave (as in flexed inward) and began to separate and open up the seam.
![](http://i1297.photobucket.com/albums/ag23/kdxGeoff/1CP2dqdp_zps1f9i22fq.jpg)
Thanks for sharing your observation with us,,,,
If the tank went concave? It is because the inside of the tank wall "grew" "expanded when wet again.
It may be reasonable to "assume" that a more realistic approach maybe to "immerse" or soak the whole tank in a "vat" so that the inside and outside can expand(and soak up) at the same rate. Maybe pulling it in and out of that "solution" over a period of days weeks or months to give the Tank a chance to normalise slowy,,,rather than Shock and Ore?
I truly believe the best way to store a plastic bike is to keep covers on them(UV protectors).
If the outside sunk and went concave, well then,,,that's a valuable shared observation