Where Do You Put the Grease for the Manual Transmission in a 1998 Nissan Frontier?. The 1998 Nissan Frontier came equipped with a 2.4-liter inline-four cylinder engine and either an automatic or model FS5W71 five-speed manual transmission. The gear oil in the manual transmission should be changed every 60,000 miles or 48 months. Check the gear oil every 12,000 miles. The transmission has a filler drain plug on the bottom of the case and a filler plug on the side of the case. This is a quick and easy job for the do-it-yourself mechanic.
Park the Frontier on a level surface and set the parking brake. If you cannot slide under it, you will have to raise the front and rear of the Frontier and support both ends with jack stands because it has to be level to get the proper amount of gear oil in the transmission.
Slide a drain pain under the transmission. Put on a pair of safety glasses and get under the vehicle. Find the drain plug in the bottom of the transmission case. Use a ratchet and 10 mm hex bit to remove the plug. Allow the gear oil to drain into the pan. Check the end of the plug and the gear oil for excessive metal flaking or chips, which may indicate excessive wear on the gears and bearings.
Wipe the drain plug clean with a shop rag. Reinstall the plug. Use a torque wrench to torque the plug to between 18 and 25 foot-pounds.
Find the filler plug. It looks just like the drain plug and is in the middle of the driver's side of the case. Remove it with the ratchet and hex bit. Use a gear oil pump – you can buy your gear oil with a built-in pump – to pump the 75W-90 gear oil into the case. Fill the case until gear oil appears at the bottom of the filler hole. Replace the filler plug and torque it to between 18 and 25 foot-pounds.
Raise the Frontier, remove the jack stands – if used – and lower it to the ground.