Checking & Changing Oil
What are the procedures for checking and changing my engine oil?
When you pour fresh oil into the crankcase, it's a golden or amber color. Gradually, the heat, dirt particles and agitated air in the crankcase cause the oil to darken. Dark oil is not only dirty; it has also lost much of its ability to coat and protect engine components.
Manufacturers recommend changing the oil in your small engine after every 25 hours of operation. For a new engine, you'll also need to change the oil after the first five hours of operation. New engines require this extra step to flush out small particles that accumulate naturally during the break-in period. Hours of use are just one factor in determining how often the oil should be changed; the amount of wear and tear is equally important. Just like the oil in a vehicle operated in extremely dirty or dusty conditions or at high speeds, the oil in a lawn mower or other small engine breaks down faster under tough conditions, such as wet grass, heavy dust, high temperatures and rough or hilly terrain.
Avoid overfilling your crankcase. Too much oil can cause the same type of engine damage as not having enough. Air bubbles form in the oil, reducing overall lubrication. The resulting friction and metal-to-metal contact can cause premature part failure. Excess oil can also burn in the cylinder, producing smoke and leaving carbon deposits.
This section covers procedures for checking and changing oil and oil filters, and offers tips on avoiding spills and choosing the right oil and other products for your engine. For oil grade information, please visit our Oil recommendations FAQ.
Checking The Oil
Make it a habit to check the oil level and appearance each time you're about to start a small engine. Checking the oil while the engine is cold and most of the oil is in the crankcase yields the most accurate reading. You won't need to change or add oil every time, but you'll ensure a better-running engine and avoid problems down the road if you keep the crankcase full and change the oil on schedule and any time the oil loses its amber hue.
Start by locating the oil fill cap on the crankcase (image A)
Image A. Fill cap locations vary, depending on the make and model of your engine. On newer models, look for an oil can symbol or the word "oil" or "fill" stamped on the plug. On small tractors, you may have to lift the hood to locate this cap.
Some engines contain either an extended oil fill tube or a standard fill hole with a dipstick for inspection. Others require you to remove the fill cap to check that the oil is at the fill line or the top of the fill hole.
To prevent dirt and debris from falling into the crankcase, wipe the area around the cap with a clean cloth before removing the cap. If there is no dipstick, dab the oil with a clean tip of the cloth to inspect the oil (image B)
If the engine includes a dipstick cap, remove the dipstick and wipe it with a clean cloth. To ensure an accurate reading, reinsert the dipstick completely. Then, remove it again and check the oil level. If the dipstick cap is a screw-in type, ensure an accurate reading by screwing in all the way before removing it a second time to check the level. The oil mark on the dipstick should be between the lines shown on the dipstick (image C)
Image C. It should never be above the FULL line or below the ADD line.
For oil checking procedures on lawnmower applications, please watch our "Checking Engine Oil - Lawnmower Engine" video:
Changing The Oil
Once you decide the oil needs changing, check your Operator's Manual to determine the type of oil, and make sure you have enough on hand. Then, run the engine for several minutes. Draining the oil while it's warm will carry off many floating particles that would otherwise settle in the engine.
Stop the engine, disconnect the spark plug lead and secure it away from the spark plug. Then, locate the oil drain plug. On mowers, the plug is typically below the deck and may be obscured by a layer of grass and debris.
Wipe the area with a rag to prevent debris from falling into the crankcase when you open the drain plug. Tilt the mower deck and position some newspaper and an oil pan or jug beneath the mower. Use a socket wrench to run the plug counterclockwise, allowing the old oil to drain (image A)
Image A. If the plug also serves as a fill cap, it may have two prongs so you can loosen it by hand or use a screwdriver or hex key for additional torque. Replace the drain plug by twisting clockwise and tightening with a box wrench or adjustable wrench.
If your engine has a filter, replace it at least once a season, more often under heavy use (see "Regular Maintenance"). Replace the filter by twisting counter-clockwise on the body, using a filter wrench or pipe wrench.
Lightly oil the filter gasket with clean engine oil. Install new filter rated for your engine. Screw in the filter by hand until the gasket contact the filter adapter (image B)
Image B. Tighten the filter an additional 1/2 to 3/4 turn.
Add the appropriate quantity of oil (see your Operator's Manual). Then, run the engine at idle and check for leaks.
After an oil change, dispose of oil and soiled rags in accordance with local environmental statutes (image C)
Image C. In many area, oil can be left at curbside with other recyclables, provided it is sealed in a recyclable container. Check the regulations in your area.
For oil changing procedures on lawnmower applications, please watch our "Changing the Engine Oil - Lawnmower Engine" video:
Typically, on vertical shaft engines, the oil drain plug is located beneath the engine block near the crankshaft. To remove the square plug, all that is required is a standard size 3/8" ratchet and extension (no socket).
On horizontal shaft engines it would be located below the centerline of the crankshaft, on the base of the engine block. Typically an adjustable wrench would remove the square plug.
PLEASE NOTE: Vertical shaft engines, Series 300 to 550, may not feature a bottom oil drain as shown above. If this is the case, oil must be poured out of the oil fill tube as outlined in your engine Operator's Manual.
Please view our "Push Mower Tune Up" video for maintenance information, including oil changing procedures:
Choose The Proper Oil
Briggs & Stratton lawnmower oil is formulated to meet the unique demands created by air-cooled 4-cycle engines. Tested and approved by Briggs & Stratton engineers. Warranty certified and recommended in all Briggs & Stratton manuals. A high-quality detergent oil classified SG/CD by the API. Conveniently sized for today's engines.
100% Synthetic Oil
SAE 5W30 Using Synthetic oil offers better wear control of your engine, even under severe operating conditions. Since synthetics have better "inherent strength" they have the ability to keep functioning at the highest level for the longest possible time.
Low Temperature Oil
Recommended for snow throwers, tractors, pressure washers, generators, and all other outdoor power equipment operated under 50 ºF (10 ºC). The Genuine Briggs & Stratton Low Temp Oil is design exclusively for your Briggs & Stratton engine.
2-Cycle Ashless Oil
A premium-quality ashless oil with gas stabilizer for use in air-cooled 2-cycle engines. Ashless-oil formulation leaves no residue and prevents plug fouling and engine deposits. Pre-diluted to mix quickly with leaded or unleaded gasoline and may be used in oil-injected systems.
For related information regarding engine break-in procedures, please visit our Recommended engine break-in procedures FAQ.
NOTE: Please read and abide by any applicable Safety Information (PDF) before performing any engine work. This information is not meant to take the place of work performed by a Briggs & Stratton Authorized Dealer. Terms and Conditions apply to all of our information provided on this website. Always be sure to read and understand your engine Operator's Manual.
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