The 18-HP Vanguard Briggs and Stratton engine features a full-pressurised lubrication system. The oil in any engine acts as the lubricant to cool the internal moving components; as the oil ages from hours of use and heat from the engine, the oil's viscosity starts to break down. As the oil breaks down, the temperature of the engine increases and will cause damage to the internal components. Change the oil and filter every 50 hours of use so your engine lives a long happy life. The procedure will take 15 minutes to complete.
Set the engine on a flat surface. Set the oil pan under the oil drain plug on the right side of the engine at the bottom.
Remove the oil drain plug with the crescent wrench and allow the oil to completely drain. Twist off the oil filter located directly in front of the oil drain plug and discard. Wipe a small amount of oil on the gasket of the new oil filter. Twist on the new filter until the filter gasket is touching the oil filter tray, then tighten an additional 1/2 turn.
Reinstall the oil drain plug and remove the oil dipstick. Place the funnel into the dipstick hole. Pour 1 1/2 quarts of oil into the engine and check the level with the dipstick. Add more oil until the dipstick reads "full." Install the dipstick and wipe off any residual oil.