You mentioned teens and single digit temps and that you put additive in the 50 gallon drum. Are you sure you put in enough or is it possible you fuel is starting to gel up? Was the type of additive used the type that prevents gelling? If your filter is see thru type see if it looks like a waxy buildup. It may be starting to gel up causing loss of power. At 200 hours have you changed the filter yet? maybe it needs it. I change mine once a year and only use the tractor about 50 hours a year. Is the 50 gallon drum stored inside or out? My guess is fuel gelling.
I have experienced problems in the past from using fuel which had had been improperly stored (absolutely my fault). I'm guessing that you have little knowledge of how long and under what conditions the fuel in that 50 gal drum was stored prior to delivery.
Now that I am in a similar situation to you (homeowner with a 28 HP tractor), I always buy my Diesel in small quantities at the pump and figure that doing things in this manner and paying extra road tax at least insures fresher fuel.
BTW, what does your manual say about the type of Diesel (ultra low sulfur?, etc.) to use?
I am a firm believer that you cannot take substandard fuel and add an additive to make it better, but I do believe you can take good fuel, add an additive, and keep the fuel good.
If it takes you three months to use 50 gallons, I would buy a couple of 5 gallon gerry cans. Diesel fuel formulas change for different times of the year. If you got summer formula, then as other say you may be having fuel issues. Interesting that I have not changed my Kubota fuel filter or air filter since I bought my used tractor (8 years ago). My only issues have been with air in the line when running out of fuel. Would not hurt to learn how to bleed the fuel line where it goes to the fuel injection pump. The Kubota is simple but if I run my Massey low on fuel, (or change the fuel filters) I have 4 areas to bleed the lines of air in a specific sequence. Good luck.
dadreier: think you're right on the fuel, given that the first (Off-Road/Marine) drum lasted nearly a year with absolutely no water or other quality issues. This drum is only 90 days old, and problems (assuming it's the fuel, and not something else I've done or not done). The manual is silent on which diesel is recommended; no information on any of the tractor decals. Once this is sorted out, your advice on small quantity buying may be the way to go. Thanks.
David: Sorry, confused your post with dadreier's. Answer on possibly going with the 5-gals. at a time stands. And, yes, my original tractor is a 1987 Kubota B5200 with ag tires. Officially rated at 13 hp, but that little tiger dragged a whole lot of whole felled trees through the woods and heavy trailer loads up grades. Unstoppable. Kept it, thank God, as I got the 2816 in winter and had the sobering experience of having to pull it out of snow in a low area with the Kubota with my wife piloting. Also never changed the air filter, and I'm not sure I even know where the fuel filter is. If I hadn't been too cheap to spend a bit more, and seduced by the weight of the Mahindra, I'd have gone with another Kubota. Such is life. Thanks.
George2615: would a general fuel additive (from Tractor Supply) include anti-gelling components? No longer have the container. Assume it can't hurt to add too much additive, or is that wrong? When this first happened, I did see what seemed like the separation line that's described for presence of water in the bowl. When I cleaned it out, there was nothing that seemed like a waxy substance however. I'm heading out tomorrow to pick up a bunch of fuel filters. Thanks.
nelsond7004: Have never drained any from the fuel tank; will try it. If I were to drain it completely (it's nearly full), and I poured that back into the drum (also 3/4 full), can I safely avoid adding water to the tractor tank if I raise the pump pipe 6 inches or so off the bottom of the drum? I'd still do as suggested and try 5 gals. of fresh product for a test. Thanks.