I’d buy a lightly used diesel before a new gas.
Big block gas is way too thirsty and gas is a PITA to haul around.
But might be good for on-site, non trailered use.
Gasser is still mighty thirsty at home, figure about 1 gallon per acre in thick spring grass, tapering down to 0.7 gallons per acre as grass thins mid-summer. But on the flip side, a homeowner may never mow enough grass in their lifetime, to make up the added cost of a diesel ZTR, in fuel savings.
The Z994R diesel with 25hp and 60" deck runs $22k. Same configuration with gasoline runs $15k, literally $7k less. The difference grows even more when comparing the 35hp models.
Diesel fuel presently costs 20% more than gasoline locally, presently $3.11 and $3.79 per gallon at our local stations. Let's pretend you're averaging 0.8 gallons/acre in gasoline mowing 130 acres of your own land per year, and that diesels use half the fuel of gassers, which might actually be pretty close to reality. With these prices, it will take you
56 years to recoup the added cost of the diesel mower, in fuel savings... assuming either mower lasted even half that long.
This is why I don't understand anyone buying diesel for personal use, whether on-road vehicles or mowers, the economics just don't work for personal use. In order to get a reasonable 5 year break-even, you need to be mowing
1460 acres per year, at the above pricing. That's a full time job, not just mowing your own yard.
Diesel will far outlast a gasser no matter what make the engine is and gassers are all guzzlers. Don't care if it's a Kowalski or a Briggs and Startem, they are all disposa engines.
I'll never defend anything made by Briggs, but the Kawi's spec'd by Deere aren't terrible. The Kawi's spec'd by some other mower brands use their weaker breather design, which can blow out and force you to do a total teardown to replace, but Deere spec's a unique crankcase breather that's much more robust.
I have 1200 hours on my Kawi V-twin, and it's still running strong. It required a new ignition coil last year ($100?), and I went ahead and put new heads and head gaskets on it, since the valve guides were starting to slip, but that was totally discretionary spending. The reality is that I could put a brand new Kawi gasoline engine on that mower every 5th year before coming close to the lifetime cost of just
one diesel ZTR.
The biggest killer of the gassers is compromised cooling, due to people not cleaning grass out of the cooling fins well enough. And that's not always the owner's fault, the design of these engines is absolutely terrible, with regard to being susceptible to grass impairing the cooling. You really need to pull all the shrounds off and blow them clean at least every 50 - 100 hours, and blow what you can from the outside between each mowing. I don't know if the diesels are better in this regard, but I have trouble imagining how they could be, all engines are susceptible to impaired cooling when the grass is flying.
