I have not noticed any coolant loss. I have not changed where I buy fuel (I buy from 2-3 different stations). The fuel filters were changed at 40,000 by the dealer. I have them changed every 10,000 miles and do oil changes every 3000. The temps during the smoke during regens have varied between 40-60 F. I am in NH. Again, this only happens during Regen and then only for a few miles.