Changing the oil in a Yamaha Big Bear can help save on wear and tear on the engine, and can even improve the Bear's performance. An engine's oil provides protection to the internal workings by thinly coating surfaces that are prone to friction. Changing the oil in a Yamaha Big Bear is fairly simple and can be accomplished by any home mechanic.
Items you will need
Wheel Chocks
Socket wrench set
Oil catch basin
New oil and filter
Park the ATV on level ground and set the parking brake. If the ATV is too low for you to slide underneath the engine compartment, drive the ATV up on a set of wheel ramps and, again, place the ATV in park.
Crawl under the ATV and locate the bottom of the oil pan, which is a rectangular metal portion of the engine normally toward the front of the ATV's engine compartment.
Find the drain plug on the oil pan and then use the appropriately sized crescent wrench to partially unscrew the drain plug.
Slide an oil catch pan under the oil drain plug and carefully unscrew the plug the rest of the way.
Allow all of the oil to drain out of the oil pan into the catch pan. When you are sure all of the oil has drained, screw the oil drain plug back in with the crescent wrench.
Locate the oil filter on the upper portion of the engine block and use an oil filter wrench to unscrew it from the engine.
Screw the new oil filter in place, tightening by hand as a wrench can overtighten the filter and damage the seal.
Locate the ATV's oil fill plug on the left side of the engine.
Pour the manufacturer's recommended amount of oil into the engine and then screw the cap back on tight.
Start the ATV, allow it to warm up for a few minutes and then check the oil gauge to make sure it is in the normal range.