How and When to Change Your Bush Hog Gear Box Oil

Tractor Mike
Tractor Mike
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Published 2022-06-09
Milky gearbox oil means there's moisture present and that's not a good thing. My bush hog had that issue, so in today's video we're going to change it.

Most brush hog gearboxes require the oil to be pumped out the top with a suction/oil extraction device like this one on my Amazon Affiliate Page: rb.gy/xfyf8i. A few of the newer machines have a drain plug in the bottom, which is nice, albeit a little difficult to reach.

So, I removed the top plug, stuck the hose in the bottom and started pumping. A lot of gearboxes have a cavity in the bottom that makes them a bit difficult to completely drain, but I must have done pretty well, because when I refilled the case, it held the full 2 quarts.

What came out of the box was a yellowish, oily substance, and when it was gone, I refilled the chamber with clean 80W-90 oil until it just slowly started trickling out of the sight plug. Then I put everything back together and I was done.

A gearbox is the most expensive part on the brush hog and very costly to repair, so you want to make sure you have good lubrication on the gear teeth and no major leaks.

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All Comments (21)
  • @HeyGunPeople
    GOOD TIP HERE - I make a New contact on my phone for all my machines. I have my truck, my M/C, golf cart, tractor, generator, etc. Then in the notes section I put Vin number, lic plate, model, oil, filter ID, and TIRE PRESSURE.. if I do maintenance I put what I did when. That way I always have my phone, I back up phone and if I am at a store and need something, I open up phone and have air filter size, oil wt, ect... it works good Since I usually fill up more tires at one time, I have a separate contact name Tire Pressure, I have all tires pressure on all vehicles, I hate trying to find and read tire PSI on bikes, lawn mowers, golf carts etc... comes in handy. Good vids, thanks for putting them out.
  • @charlesrose7212
    Get down! We even got some “Tumbling Tumbleweeds”! You’re awesome, Tractor Mike! 😀
  • @RurallyRetreated
    Although we are a little long in the teeth, we are new to tractors and implements. Your content is invaluable to us. We thank you for sharing your years of experience and wealth of knowledge!
  • @upstategearheads
    Only thing I would add to it Mike is that I would run the brush hog for a few minutes prior to changing the oil. If it's been sitting for a while the water will settle to the bottom and that will be the most difficult part to change, and the warmer oil will have a thinner viscosity making it easier to suck out
  • @matthewsims359
    It just makes me feel good when i do stuff like that. My dad was a huge grease fan. When i was a kid, i loved driving tractors. My dad always made me grease it before i was allowed to drive it. Now that i am adult with equipment of my own, i just feel good that i service everything regularly. It only takes a few mins and will keep your equipment ready to work instead of ready to be worked on.
  • @jimmccullough1051
    Great tip on marking with a paint pen. I have done that on mower decks with the blade bolt size, and any other tools needed. Nothing worse than lifting mower deck, supporting, and crawling under to find out you brought the socket for the other mower deck, because, of course, they couldn't all be the same size.
  • @TheJeepinDad
    Precisely what I needed and when I needed it. Gold! Thank you!
  • @heavymetalrockman
    Nice how-to vid Mike. Only suggestion I could add is to wrap that oil level plug with some teflon tape to prevent leakage and to make it easier to remove for the next time.
  • @hightail5313
    I noticed your bush hog is a few inches wider than your tractor's width. After taking out too many fence posts and scarring too many trees I found a mower that stays inside my tractors footprint. Thanks for the oil change tip Mike!
  • @jerrygilliam7349
    Thanks for the tips and reminder Mike. I bought a new flail mower in 2019. I've checked the oil level before each season's first use. But, I think I'm due for an oil change.
  • @stevewarner8880
    Mike, as I have commented before. I have that same cutter. I do one thing differently. I remove the 4 small bolts out that hold the top cover on the gearbox. Actually I remove 3 and back one off and swing the cover out of the way. This allows for a better inspection of the gearbox internals and easier manipulation of the suction gun. When we had seals leaking on gearboxes at the state Highway dept we would take the top covers off and squeeze gun grease tubes into them. We could finish the road and change the seal when we got back to the shop
  • @rgrubbs
    Very helpful and right on time!
  • @StephenBauerHomestead
    I am not sure of why I never heard of changing oil in the bush hog. I have had mine for 17 years and it runs perfectly. I just keep it topped off. Thanks for the video!
  • @MattN03
    Great video Mike! I like to check that my fill plug will come loose before i drain the oil, just in case there is an issue with the fill plug stripping.