can someone verify my math please.

You're going to find out, just like lots of others have, that there's no product on the market that's going to magically increase your mileage. Assuming that everything in the fuel system is clean and working properly.

YOU have the best effect on fuel mileage. Mostly through the WAY the truck is driven. Not knowing the particulars on your rig, I can only suggest that you look at the power/torque vs. road speed for your engine and make adjustments in your driving habits. Slowing down is a way to see a major improvement in fuel milage.

 

Run an injector cleaner once a month, biocide (algae) once a quarter, and use the 2 stroke every fill up. Have a couple sets of filters along when you do the biocide. My wife made a spreadsheet that calculates each tank and keeps a running total for each month. Each month is on it's own page, then there's a page at the end that the monthly totals pop up on and does a yearly total. Really cool and nice to have, beats the hell out the notebook I had. Many thanks to my wife.