My TM is black. Never had white streaks.
Is your water hard, and could these be hard water streaks?
Check your roof sealant. It can cake and crack over time. Even though our coach is not yet 2 years old the sealant around all roof joints, appliances, and holes for the horns and refrigerator were all deeply cracked.
Last, do you park under anything that might "bleed" on the roof?
07 TM 40D;ISL 450 Cummins(upgraded). Very happy w/coach
Gnarly toad to scoot around.
Geocaching, hiking, fishing, National Parks, Civil War sites.