From my experience using both geared and HST 60HP tractors I averaged a difference of about 2 gallons diesel per ~12 hour day. At $3/gallon thats $6/day
Lets assume you don't use your tractor much and you fill the tank once a week. 50 weeks x $6 = $300
Here's another way to look at it. Each gallon of diesel consumed generates 19.64 lbs of
CO2. So thats approx. 40 lbs x 50 weeks = 2,000 lbs or 1 ton CO2 difference.
Since you don't care about fuel economy and money how about sending me an e-transfer $6 per week? I think that'll cover a McPuky's burger once a year...