Things You'll Need
Service stand or a 3-inch block of wood
Parts cleaning spray
Cap-style oil filter wrench
3 quarts 20W50 motor oil
As part of a basic maintenance program, changing your Harley-Davidson Heritage Softail Classic's engine oil regularly will prolong the service life of the engine and its internal parts. In order to keep the Softail's engine at its peak operating condition, its oil and filter should be replaced every 2,500 miles to prevent oil degradation, which can lead to premature wear. The procedure is similar for both the Evolution engine-equipped models and the newer Twin Cam-equipped models; however, the location of the oil drain plug will differ.
Warm your Heritage Softail's engine and oil. Start the engine and let it idle in place for three minutes, then stop the engine. Mount your Heritage Softail on a service stand, or place a 3-inch block of wood under the motorcycle's side stand to elevate it into an upright position.
Push down on the oil tank filler cap, then twist the cap counterclockwise to unlock it from the oil tank filler neck. Pull the cap and its attached dipstick out of the oil tank to vent the oil system.
Locate the oil drain plug. Softail models built between 1984 to 1999 are equipped with an Evolution engine, which uses an oil drain hose placed in front of the transmission unit, on the left side of the motorcycle. Softail models built after 2000 are equipped with the newer Twin Cam engine, placing the oil drain plug on a cross-member below the rear of the transmission unit.
Place an oil drain pan under the oil drain plug or hose. Unscrew the drain plug with a 5/8-inch socket and a socket wrench, or loosen the drain hose clamp with a flat-head screwdriver and pull out the hose plug. Allow your Heritage Softail's oil to drain for a minimum of five minutes or until the flow of oil slows to a thin trickle.
Clean the drain plug with a shop towel and replace its sealing O-ring with a new O-ring. Screw the drain plug into the cross-member, by hand, then tighten it to 20 foot-pounds with a 5/8-inch socket and a torque wrench -- this step applies only to Softail models equipped with a Twin Cam engine.
Wipe the drain hose with a shop towel, then push the hose plug into place. Tighten the drain hose clamp with a flat-head screwdriver -- this step applies only to Softail models equipped with an Evolution engine.
Clean the area around the oil filter and the oil pump, located on the front left side of the engine, using a parts cleaning spray. Loosen the oil filter with a cap-style oil filter wrench, then unscrew the oil filter by hand. Clean the oil pump's mating surface and threads with a parts cleaning spray, then wipe dry with a shop towel.
Unpackage your new oil filter and pour up to four ounces of 20W50 motor oil into the filter. Let the filter's paper element absorb the oil for one minute, then spread a thin coat of oil around the oil filter's sealing O-ring. Screw the oil filter into place, by hand, until it is seated against the oil pump. Tighten the oil filter an additional quarter-turn, by hand. Wipe away any spilled oil with a shop towel.
Place a funnel into the oil tank filler neck, then fill the tank with 2.6 qts. of 20W50 motor oil. Remove the funnel from the oil tank. Push the oil filler cap and dipstick into the filler neck, then twist it clockwise to lock it in place.
Start the engine and let it idle for another three minutes, then stop the engine. Remove the oil cap and wipe its dipstick clean with a shop towel. Reinsert the dipstick into the oil tank filler neck until the cap is resting on the filler neck's rim. Withdraw the dipstick and take note of the oil level in relation to the upper and lower marks cut into the dipstick. If the oil level is below the lower mark, add a small amount of 20W50 motor oil into the oil tank, then recheck the oil level. Wipe the dipstick again with a shop towel, then reinstall the oil cap if the oil level is situated between both marks.