Mine is getting medicated. We have two places to buy off road diesel nearby. I don't like driving it on salty roads. For reasons of price, quality, and people I like, I prefer one. My son prefers the other.
Last weekend in the storm, Town, and State roads were being plowed, but not salted. Seemed to accumulate 4" between plow runs. Seth decided it was a good time to put 36 gallons of fuel. "Lady" who runs the store grew up in a construction family, she knows better. I believe she is buying summer diesel, selling it as winter fuel. In past, fuel sellers used kerosene to protect against gelling. Now they use additives. I guess non gel agents, alcohol to prevent formation of ice crystalls. He did put Howe's fuel treatment in it. I don't think he ran it around enough to thoroughly work it through the fuel system.
Next day it wouldn't start without charging batteries, it was cold outside! I checked, the batteries are Case, 9 years old. I went off to buy new ones. Of course the new ones didn't easily fit. An extra little rim at base made them too wide. Tractor sat after getting the batteries in.
Yesterday, it started, ran fine 20 minutes, then quit, wouldn't restart. Three hours later, warmed filters, a dose of diesel 911, ($20.), dried everything, it ran, with the water in filter alarm screaming. Took the water separator off, dried it out thoroughly, alarm went away.
I'll run this tank of fuel out before new fuel filters, likely be warmer weather by then.
She is saving herself money buying untreated fuel. She's making money selling Diesel 911, and fuel treatment, costing customers money & time.