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How to Change the Transmission Fluid in a Sears Lawn Tractor

Lawnmower tracks image by Jim Mills from

Every year before the mowing season begins, you should inspect your Sears lawn tractor and perform any necessary servicing and maintenance on it. It's also a good idea to make sure the transmission fluid is full in the rear axle crankcase. It's advised to replace your transmission fluid every four years as it will begin to lose its viscosity and break down at this point.

Park your Sears lawn tractor on a level surface.

Position yourself behind the rear axle of your Sears lawn tractor. Locate the basketball-shaped transmission (crankcase) on the rear axle.

Unscrew the square drain plug on the base of the crankcase with the proper sized wrench. Allow all the transmission fluid to drain out into the drain pan. Screw the plug back in tightly.

Unscrew the bolt on the top of the crankcase with the proper sized wrench to expose the fill hole. Insert a funnel into the hole. Fill the crankcase with lawn mower crankcase oil (transmission fluid) until it is to the bottom of the bolt screw hole. Screw the bolt back in tightly.

Fill A Hydrostatic Transmission In A Lawn Tractor

The hydrostatic transmission in your lawn tractor requires servicing that includes draining the old hydrostatic oil, changing the filter and adding new hydrostatic oil. Set the lawn tractor park brake to prevent the lawn tractor from shifting or rolling while working. Slide an oil-catch drain pan directly under the hydrostatic transmission oil drain plug to catch the old transmission oil. The transmission oil drain plug is generally located on the side of the transmission towards the bottom. Some hydrostatic transmissions have more than one transmission oil reservoir located under the lawn tractor seat: one that fills the hydrostatic transmission side and the other fills the differential gear side. Torque the transmission oil drain plugs with a socket and torque wrench. Unscrew the hydrostatic transmission oil filter from the transmission oil filter housing with an oil filter wrench. Slide the oil filter wrench onto the oil filter. Screw the new oil filter onto the oil filter housing by hand. Fill the oil reservoir to the full line that is embossed on the side of the reservoir tank. Stop the lawn tractor engine and check the hydrostatic transmission oil level.

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