Kerosene/Diesel Transmission Flush

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Mar 25, 2008
Kansas City Metro
I've got a 1980 Wheel Horse C-145 with the 8 speed trans. When I bought the tractor two years ago it has some water in it because the shift boot had some dry rot and someone left it outside for several years. I changed the trans oil which got most of the water out but I'm switching over to a sythetic gear oil for this winter and I'd like to flush it out really well. Can I fill the trans with kerosene or diesel and drive it around the yard for a few minutes before putting the gear oil in? I wouldn't think it would hurt anything since it would be quick but I thought I'd get some other opinions. Which would work better, kerosene or diesel?
Ten years ago, I did the same thing with my Case, model "D" tractor. It had the original factory fill gear oil in the tranny which, aside from being very old, was contaminated with water.

I drained all ten gallons of gear oil from the rear end, filled with a 50/50 mix of diesel fuel and used motor oil. I then drove around the farm for about twenty minutes, drained out the mix and refilled the transmission/rear end with ten gallons of used motor oil, (yes, I had been saving this oil for just this reason). I drove around again for about twenty minutes, drained the used oil from the transmission/rear end and refilled with the proper gear oil.

Ten years later, Mighty "D" is still running strong.

With a wheel horse, you might be able to jack it up and during your "flush" simply let the wheels spin with no load whatsoever. Be sure wheel horse is secure so it doesn't fall, hit the ground running and run over something, (like you or anyone else who might happen to be there). Also, be very careful of the spinning wheels. As I recall, the wheel horse tires are a chevron design. If one of the chevrons grabs you, (i.e. loose clothing), it WILL pull you in. That would be bad.

I do want to point out that you are taking a gamble by doing this. Depending on age/condition of the machine, it might be on it's way out and this would speed the process. Obviously, it's your call.

Just an additional note - make sure your tranny lube system is restricted to the transmission itself and does not circulate in any other part of the machine. If it's a typical manual transmission that is a closed system, you should be okay. If it circulates in other parts of the machine, (some "Deutz" tractors are like this), then I would be wary of a "diesel" or "kerosene" flush).
I drained my 64 John Deere 110 and then added 1qt of kerosene and drove around my yard for a few minutes in each gear, then drained the kerosene, which looked like chocolate milk by then and then filled with Mobil 1 75w90 and it has done great for 3 years now.
Those Wheel Horse 8-speeds are tough as nails, like all the old school garden tractor gear boxes. I'm sure kero or diesel wouldn't ruin them, but I'd still be inclined to just run warmed 75w90 gear oil through it a few times. Buy the least expensive 75w90 you can find and warm the bottles in hot water. Maybe warm the trans case too with a heat lamp or heat gun as well, just to make the gear oil flow easily.
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