#1 red

I was serious about asking if it is bio-fuel ...
I run B-20 here on my farm and the tractors seem to like it -- tho I keep smelling french fries and that makes me hungry, ...LoL
the bio-fuel attracts water pretty bad, and that storage tank may have not lived in the best conditions

Before you put any in your truck, tilt the tank so you can tap off some from the bottom into a clear container (gallon or whatever)
if the fuel is free of water and clear -- your good

If the fuel has water or is murky -- dispose of the sample (makes a good week killer) and tap off another sample
the goal here is to get any water out, along with other crud that has settled in the bottom of the tank

If you have drained out a few samples from the bottom and the fuel is still murky -- then get some Bio-cide (EDIT: Power Service Clear Diesel - white bottle) and treat the tank - be sure to stir the tank -- sample again in a few days

Be sure to add a quart of oil to each tank you put in your truck for extra lubrication -- Trans, 2-stroke, or engine oil