Where to find the transmission dipstick and what the fluid level should be

The 1998 Polaris Explorer 400 has a transmission dipstick located on the right side of the engine, near the frame. To check the level, you need to pull the dipstick straight out—it has a handle you can grip. The dipstick itself is marked with two lines: a minimum line and a maximum line. Your fluid should sit between these two marks when the engine is cold and the ATV is on level ground.

If the fluid is below the minimum line, you need to add transmission fluid. Do not overfill past the maximum line. Overfilling can cause the fluid to foam inside the transmission, which reduces its ability to cool and protect the gears. This leads to overheating, slipping, and premature wear.

Key Takeaways

  • The transmission dipstick on the 1998 Polaris Explorer 400 is located on the right side of the engine and must be checked with the engine cold and the ATV level.
  • Polaris recommends Polaris Synthetic Automatic Transmission Fluid (ATF) or an equivalent ISO 46 synthetic fluid for this model.
  • Add fluid slowly through the dipstick tube using a funnel, checking the level after each small amount to avoid overfilling.
  • Transmission fluid breaks down over time and should be changed every 500 to 1,000 miles of riding, depending on conditions.
  • Low transmission fluid causes slipping, delayed engagement, and overheating; overfilling causes foaming and the same damage.

What type of transmission fluid the Explorer 400 uses

The 1998 Polaris Explorer 400 requires Polaris Synthetic Automatic Transmission Fluid, or an equivalent ISO 46 synthetic fluid. Polaris part number for their own fluid is 2873139. You can also use other brands that meet ISO 46 viscosity, but synthetic fluid is important—it handles the heat and pressure inside the transmission better than conventional fluid and lasts longer.

Do not use automotive transmission fluid (ATF) from a car or truck. The viscosity and additive package are different, and using the wrong fluid will cause shifting problems and transmission damage. Check the bottle or container to confirm it says ISO 46 or that it is rated for Polaris ATVs.

How to add transmission fluid safely

Park the ATV on level ground and let the engine cool completely. A warm engine will give you a false reading on the dipstick. Remove the dipstick by pulling it straight out, then wipe it clean with a lint-free cloth or paper towel.

Reinsert the dipstick all the way until it seats, then pull it out again to read the true level. If the fluid is below the minimum line, place a small funnel into the dipstick tube opening. Pour transmission fluid slowly—about a quarter cup at a time—then wait a few seconds and check the level again with the dipstick. Repeat this process until the fluid reaches the maximum line.

Do not pour fluid in a hurry or overfill. Once you reach the correct level, wipe the dipstick clean, reinsert it fully, and make sure it is seated. Wipe up any spilled fluid from the engine or frame to prevent dirt from sticking to it.

Why transmission fluid level matters for the Explorer 400

The transmission in the 1998 Polaris Explorer 400 is a continuously variable transmission (CVT). It relies on fluid pressure to move the belt and pulleys that change the gear ratio as you accelerate or climb. When the fluid level drops, pressure falls, and the transmission cannot hold the belt in the right position.

Low fluid causes the transmission to slip—you press the throttle but the engine revs without the ATV accelerating smoothly. You may also notice delayed engagement when you shift from neutral to forward or reverse. Over time, slipping generates heat, and a hot transmission wears out fast. Replacing a CVT transmission is expensive, so keeping the fluid at the correct level is one of the cheapest ways to protect it.

Overfilling is equally harmful. Extra fluid has nowhere to go inside the transmission case, so it foams and churns. Foam does not transfer pressure or heat as well as liquid, so the transmission overheats and the belt slips. The result is the same damage as running low.

How often to check and change transmission fluid

Check the transmission fluid level before every ride or at least once a month if you ride regularly. Checking takes two minutes and can catch a slow leak or fluid breakdown before it damages the transmission.

Change the transmission fluid every 500 to 1,000 miles of riding, depending on how hard you ride and the conditions. Riding in mud, water, or dust causes the fluid to break down faster. If you ride in those conditions often, change the fluid every 500 miles. If you ride mostly on dry trails or roads, you can go closer to 1,000 miles. Refer to your owner's manual for the exact interval recommended for your riding style.

Transmission fluid darkens and loses its ability to protect as it ages. Dark, burnt-smelling fluid is a sign that the transmission has been running hot or the fluid is overdue for a change. Do not wait until the fluid looks black—change it on schedule to keep the transmission cool and responsive.

Signs that your transmission fluid needs attention

If the transmission slips—the engine revs but the ATV does not accelerate smoothly—check the fluid level first. Low fluid is the most common cause of slipping on the Explorer 400. If the level is correct but slipping continues, the fluid may be burnt or the transmission may have internal damage.

A burning smell from the engine area, especially during hard riding or climbing, usually means the transmission is overheating. This happens when the fluid is low, overfilled, or too old to cool properly. Stop riding when ready and check the fluid level. If the level is correct, the fluid may need to be changed.

If the ATV is hard to shift into forward or reverse, or if it hesitates before engaging, low or dirty fluid is often the cause. A fresh fluid change sometimes restores smooth shifting. If shifting remains sluggish after a fluid change and the level is correct, have the transmission inspected by a Polaris dealer.

Frequently Asked Questions

Can I use regular automotive transmission fluid instead of Polaris fluid?

No. Automotive ATF has a different viscosity and additive package than Polaris Synthetic Automatic Transmission Fluid. Using the wrong fluid will cause shifting problems, slipping, and transmission damage. Always use ISO 46 synthetic fluid rated for Polaris ATVs or Polaris brand fluid itself.

What if I accidentally overfill the transmission?

Remove the dipstick and use a clean turkey baster or small syringe to draw out the excess fluid until the level reaches the maximum line. Overfilled fluid will foam and cause the transmission to overheat, so correct it as soon as you notice it.

How do I know if my transmission has a leak?

If the fluid level drops between rides and you have not ridden hard or in water, you likely have a leak. Check under the ATV for red or pink fluid on the ground or frame. A slow leak may only show a few drops. Have the transmission inspected by a dealer to find and repair the leak before the fluid level gets too low.

Can I check the transmission fluid while the engine is warm?

No. Warm fluid expands and will read higher on the dipstick than it actually is when cold. Always check with the engine cold and the ATV on level ground for an accurate reading. If you just finished riding, wait at least 30 minutes before checking.

What should I do with old transmission fluid after I drain it?

Take used transmission fluid to a recycling center, auto parts store, or hazardous waste facility. Many auto parts stores accept used fluid for free. Do not pour it on the ground or into a drain—it is toxic and harms soil and water.