The tank i useded from texas to nevada 60 gal if i have to clean the tank how do i do that . Allso how would i know if it is clean diesel every sinc i used the tank i always put standyne diesel additive that is suppose to help with storing the diesel in my tank. The tank is right up against my back window in the truck bed. When i am not pulling my 5th wheel i have atonue cover over it. I am currently working in the nevada desert temps should be no more than 98 degrees at this elevation.How long will the diesel in my tank last.