Wheel horse 8hp 4 speed trans oil change

[Dakota 70]

Hello everyone I have a wheel horse 8hp 4 speed that I got about a week ago and I need to change the trans oil ( it looks like muddy water). I was told that to change it I need to drain the old oil and then to get everything cleaned out of the gears to pour in some diesel fuel, drive it around in all 4 gears, then drain the fuel, and then repeat 4 times. What I need to know is the best place to add the new oil, what type of gear oil, and how much. And info would be apreciated, thanks!

[rmaynard 15,610]

Your 1973 8hp 4-speed takes 1-1/2 quarts of SAE 90-140 or 80/90 A.P.I. Service GL-5 Gear Lubricant. The best place to add oil is through the shifter hole with the shifter removed. When draining the old oil and subsequent diesel fuel solution, be sure to raise the front end of the tractor so that all the fluid in the front of the transmission can run over the hump in the middle of the transmission and toward the drain hole in the back. Your transmission has a drain plug in the bottom that requires a 1/4" Allen wrench to remove.

[rmaynard 15,610]

Just another word on filling transmissions. The 4-speeds such as yours can also be filled via the filler plug on the left side, rear of the transmission. However, 8-speeds require 2 quarts of oil and must be filled through the dipstick tube or shifter hole, as only 3 pints can be added through the filler plug without running back out.

[peter lena 8,734]

glad you are getting after this , its simple and basic, that drain plug is lower left hand corner , facing rear of tractor. its an Allen plug , so its probably packed with dirt, dig it out, for access. don't wait for failures, keep an eye on things and replace parts before you need them. Maynard's oil info was spot on , good luck on this service , pete 

[Dakota 70]

@rmaynard So the plug on the rear left side isn’t the actual drain plug? When I loosened it alittle bit that’s when the muddy water looking oil came out so i just assumed it was the drain plug. It’s just a square head not the Allen head as you decribed. Thanks for you the help also! @peter lena

Edited May 29, 2018 by Dakota

[rmaynard 15,610]

That is correct. The reason the murky mess ran out is because water has raised the level of fluids above the 3 pint level. After you have finished draining, flushing and filling, be sure to replace the shifter boot with a new one to prevent water from getting in again. Because of changes in temperature and humidity, there will always be a small amount of moisture inside the transmission. But regular draining and refilling will keep that to a minimum.

[Dakota 70]

Oh ok that’s makes sense, the tractor is always stored inside so replacing the shifter boot isn’t that high of a priority right now because there are a few more important things I need to get first