How to Change Polaris Sportsman Gearcase Fluids

Changing the transmission and diff fluids in your Polaris Sportsman is an important part of its routine maintenance schedule. 

Drive system fluids break down over time, causing greater wear on the precision parts in your drivetrain. Changing these fluids can prevent that from happening. Polaris recommends changing the drive system fluids in your ATV after every 50-75 hours of use.  

Here's how to change the transmission and diff fluid on your Polaris ATV.

Tools and Parts Needed - Polaris Sportsman Drive System Fluid Change


Polaris Sportsman Front Gearcase Fluid Change

Step 1. Remove the 8mm Allen fill bolt for the transmission. See #23 in the front gearcase diagram for the Sportsman 850. 

PRO TIP: We removed the front wheel on our Sportsman so you can see the process, but it's not necessary for you to remove the wheel on your ATV. 

Polaris Sportsman front gearcase fluid change

Step 2. Get a drain pan to catch the fluid, and remove the 8mm Allen drain bolt located underneath the front differential. Check the fluid to make sure it's not milky, which is an indication of water in the transmission. Once the fluid has completely drained, replace the drain bolt. 

Polaris Sportsman gear case fluid change

Step 3. Insert one end of the clear tube into the fill bolt opening, and attach the other to the hand pump. Use the hand pump to fill the gearcase with Demand Drive fluid.

NOTE: The tank holds about 10 ounces, or roughly a third of the bottle. You'll know it's full when the fluid starts to run out of the opening. When it's full, replace the fill bolt. 

Polaris Sportsman Demand Drive fluid change

Active Descent Control Fluid Change

Step 1. Remove the front storage compartment. Flip up the two anchors located inside the compartment, then close the compartment back to make it easier to lift it straight off the nose of the unit. 

Polaris Sportsman active descent control fluid change

Polaris Sportsman 850 gearcase fluids change

Step 2. Remove the plastic cover over the reservoir cap. To do this, remove the two Torx head bolts and pull the cover away.   

Polaris Sportsman ATV active descent fluid change

Polaris Sportsman transmission fluids change

Step 3. Remove the reservoir cap and the rubber seal underneath. It is the yellow cap on the right as you face the front of the unit. 

Polaris Sportsman gearcase fluid replacement

Polaris ATV gearcase fluid replacement

Step 4. Flush the system by first topping off the reservoir with Demand Drive fluid.    

Polaris Sportsman Demand Drive fluid flush

Step 5. Locate the bleeder valve in the wheel well of the unit. There is one on either side, so you can choose which one you prefer. Remove the dust cap, then place a box-end-wrench over it and attach a length of clear hose. 

Polaris ATV demand drive fluid change

Step 6. Turn the wrench to the left to open the valve so the fluid will drain. 

NOTE: It's important that you keep adding fluid up at the reservoir during the draining to keep fluid in the system. You do not want it to run dry. 

Polaris Sportsman demand drive fluid drain

Step 7. Once you've flushed it and seen 4-5 ounces drain through the bleed valve, close the valve by turning it to the right. Next, replace the seal and the yellow cap at the top at the reservoir.  

Polaris ATV trans and diff fluid change

Step 8. Replace the cover and its two Torx screws. Next, replace the cargo compartment and secure it by closing the two anchors inside.   

Polaris Sportsman 850 trans and diff fluid change

Polaris Sportsman 850XP trans and diff fluid change

How to Change the Transmission Fluid on a Polaris ATV

PRO TIP: We removed the rear tire and skid plate to make it easier for you to see what's going on. While it's not necessary, removing the skid plate can help make this job a little less messy. Check out our Polaris Sportsman 850 rear skid plate diagram to see how it's attached.

Step 1. Find the drain bolt and fill bolt by looking at the transmission from right rear. Get a drain pan underneath the transmission and remove both bolts. 

NOTE: Make sure you get your Allen inserted completely into the head of the bolt, otherwise it could strip.  

Polaris Sportsman ATV transmission fluid change

Polaris Sportsman transmission fluid drain

Step 2. Clean off the magnet on the drain plug to capture any filings from inside the transmission, then replace it in the transmission housing. 

Polaris ATV transmission fluid drain plug

Polaris ATV transmission fluid drain

Step 3. Fill the transmission with Polaris AGL gearcase lube using your hand pump. It will take about 37 ounces, so you'll need two bottles. You'll know it's full when fluid starts to run out of the opening.  

Polaris ATV transmission fluid service

Polaris Sportsman 850 transmission fluid drain

Step 4. Replace the fill plug and tighten it to 12-14 foot-pounds. Do not overtighten it.  

Polaris Sportsman Rear Diff Fluid Change

Step 1. Get a drain pan underneath, and remove the rear diff drain and fill plug bolts. Wait for the differential to completely drain. 

Polaris Sportsman rear diff fluid change

Step 2. Clean and replace the drain plug after the differential is finished draining. 

Polaris Sportsman rear differential fluid change

Step 3. Follow the same process you used to fill the transmission, but use Polaris Angle Drive fluid instead. Again, you'll know it's full when fluid begins to run out of the fill plug opening.   

Polaris ATV rear diff fluid change

Polaris ATV rear differential fluid change

Step 4. Replace the fill plug and you're done. 

Polaris Sportsman ATV rear diff oil change


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