How to Change Oil in a Briggs and Stratton Lawn Mower
Changing oil in a Briggs and Stratton lawn mower is a straightforward maintenance task that takes 15–20 minutes. Warm the engine for 15–20 seconds and turn it off, locate the oil drain plug (usually on the side or bottom of the engine), place a drain pan underneath, and remove the plug to drain old oil completely. Replace the oil filter if your model has one, reinstall the drain plug, and refill with the recommended oil grade (typically SAE 30 for warm weather or 10W-30 for multi-season use) to the level shown on the dipstick. Most Briggs and Stratton models hold 16–20 ounces of oil.
Before You Start: Tools, Materials, and Safety
Proper preparation ensures a clean, safe oil change. Gather the following items before you begin:
- Oil drain pan – catches used oil and prevents spills
- Socket wrench or adjustable wrench – fits the drain plug (typically 14mm or 16mm)
- Oil filter wrench – only needed if your model has a spin-on oil filter
- Fresh oil – SAE 30 (warm weather) or 10W-30 (multi-season); check your owner’s manual for the correct grade and quantity
- Oil filter replacement – if applicable to your model
- Funnel – prevents spilling when pouring new oil
- Rag or paper towels – for cleaning and wiping the dipstick
- Level surface – ensures accurate dipstick readings
Always warm the engine slightly before draining (15–20 seconds of idling). Warm oil flows more freely and carries away more contaminants. Never drain oil from a hot engine—let it cool for 5–10 minutes first to avoid burns.
Why Regular Oil Changes Matter for Briggs and Stratton Engines
Oil lubricates engine parts, removes debris, and regulates temperature. Over time, oil breaks down and accumulates dirt, sludge, and metal particles that damage the engine. Briggs and Stratton recommends changing oil every 50–100 operating hours or at least once per season for residential mowers. Regular oil changes extend engine life, improve performance, and prevent costly repairs.
Locating the Oil Drain Plug and Filter
Drain plug location varies by engine orientation and model type.
Horizontal Shaft Engines
Common in push mowers, the drain plug is typically located on the side of the crankcase. Look for a bolt protruding from the lower side of the engine block. Some models have the plug on the bottom; in that case, you may need to tilt the mower to access it (tilt toward the carburetor side to avoid flooding the air filter).
Vertical Shaft Engines
Found in zero-turn and some walk-behind mowers, the drain plug is usually on the bottom or side of the engine. These engines often sit higher off the ground, making plug access easier.
Oil Filters
Not all Briggs and Stratton models include oil filters. Older models and budget-friendly engines typically use filterless designs. Professional-grade and larger displacement engines (Twin Power, Intek models) often have spin-on oil filters located on the side or top of the engine. Consult your owner’s manual to confirm whether your model has a filter.
Step-by-Step: Draining the Old Oil
Step 1: Prepare the Engine
Run the engine for 15–20 seconds to warm the oil, then turn it off. Warm oil drains more completely and carries away more sludge. If the engine is too hot, wait 5–10 minutes before proceeding to avoid burns.
Step 2: Position the Drain Pan
Place a drain pan directly under the drain plug. Position it to catch all draining oil without spillage. Old oil is slippery and can stain concrete and harm the environment.
Step 3: Remove the Drain Plug
Use a wrench (typically 14mm or 16mm) to loosen the drain plug counterclockwise. Once hand-tight, unscrew it slowly to avoid splashing. Let the plug fall into the drain pan if it’s warm. Allow 5–10 minutes for old oil to drain completely. Tilt the engine or mower slightly if needed to drain all oil.
Step 4: Clean the Drain Plug
Wipe the drain plug with a rag to remove old oil and debris. Inspect it for cracks or damage; replace if necessary. A faulty plug can cause leaks.
Step 5: Reinstall the Drain Plug
Screw the drain plug back in by hand, then tighten it firmly with a wrench. Do not overtighten—this can strip threads or crack the plug. Snug is sufficient.
Replacing the Oil Filter (If Applicable)
If your Briggs and Stratton model has a spin-on oil filter, replace it during every oil change.
Removing the Old Filter
Locate the filter (usually a cylindrical cartridge on the side of the engine). Position a drain pan underneath to catch residual oil. Use an oil filter wrench to loosen the filter by turning counterclockwise. Once hand-tight, unscrew it slowly and let it drain into the pan for a minute.
Installing the New Filter
Clean the filter mounting surface with a rag to remove old gasket material and debris. Apply a thin layer of new oil to the rubber gasket of the replacement filter (this helps create a proper seal). Screw the new filter on by hand until the gasket contacts the mounting surface, then turn an additional three-quarter turn. Do not use a wrench—hand-tightening is sufficient and prevents over-compression of the gasket.
Refilling with Fresh Oil: Type and Amount
Choosing the Right Oil Grade
Briggs and Stratton engines typically require SAE 30 or 10W-30 oil, depending on temperature and season:
- SAE 30 – recommended for warm weather (above 40°F); thicker oil that provides better protection in high temperatures
- 10W-30 – multi-season oil suitable for temperatures between 0°F and 100°F; flows well in cold conditions and maintains protection in heat
- SAE 5W-30 – for extreme cold climates (below 0°F); flows easily at startup but may not provide adequate protection in very hot weather
Always consult your owner’s manual for the exact grade recommended for your model and climate. Using the wrong oil grade can reduce engine performance and lifespan.
Oil Capacity
Most residential Briggs and Stratton mowers hold 16–20 ounces (0.47–0.59 liters) of oil. Check your manual for the exact capacity. Overfilling can cause oil to enter the combustion chamber, leading to smoking and poor performance. Underfilling leaves bearings unlubricated, causing rapid wear.
Adding New Oil
Insert a funnel into the oil filler cap (usually a large bolt on top of the engine). Pour new oil slowly, pausing halfway to check the level with the dipstick (see next section). Add oil gradually to avoid overfilling.
Checking Oil Level: The Dipstick Method
Accurate oil level is crucial for engine health. Place the mower on a level surface and wait 30 seconds after refilling for oil to settle.
- Pull the dipstick straight out and wipe it clean with a rag
- Reinsert the dipstick fully into the filler tube
- Pull it out again and observe the oil level against the minimum and maximum marks
- The oil should reach the maximum mark; if below the minimum, add a small amount and recheck
- Never overfill—excess oil will leak or enter the combustion chamber
Wait 10–15 seconds between checks to allow oil to drain back from the engine walls and provide an accurate reading.
Post-Maintenance Checks and Tips
Verify Everything Before Starting
- Ensure the drain plug is tight and the oil filter (if applicable) is secure
- Check that the filler cap and dipstick are reinstalled properly
- Confirm the oil level is at the maximum mark on the dipstick
- Look for leaks around the drain plug and filter before starting
Test Run
Start the engine and let it idle for 30 seconds. This circulates the new oil throughout the engine. Check again for leaks around the drain plug and filter. If leaks appear, turn off the engine, tighten the plug or filter, and recheck.
Dispose of Old Oil Responsibly
Never pour used oil down drains, into soil, or onto pavement—it harms the environment and is illegal in most jurisdictions. Instead:
- Take used oil to a local recycling center (most accept it free)
- Check Earth911.com or your municipality’s website for nearby drop-off locations
- Some auto parts stores (AutoZone, Advance Auto Parts) accept used oil at no charge
- Store old oil in a sealed container away from children and pets until disposal
Model-Specific Variations
Horizontal vs. Vertical Shaft Engines
The main difference is drain plug access. Horizontal shaft engines (push mowers) may require tilting to access bottom drains—always tilt toward the carburetor side to prevent air filter flooding. Vertical shaft engines (zero-turns) typically sit higher, making drain plug access simpler.
Professional-Grade Models (Vanguard, Intek Pro)
Larger displacement engines with spin-on oil filters follow the same procedure but may hold 24–28 ounces of oil and require filter replacement every 100 operating hours. Refer to the specific model’s manual for exact capacities and intervals.
Older vs. Newer Models
Newer Briggs and Stratton engines often include spin-on oil filters and clearer labeling of drain plugs and filler caps. Older models (pre-2010) typically use filterless designs and may have smaller oil capacities (12–16 ounces). Always consult the owner’s manual for your specific model year.
Common Mistakes to Avoid
- Overfilling oil – causes smoking, poor performance, and oil leaks
- Using the wrong oil grade – reduces protection and engine efficiency
- Over-tightening the drain plug or filter – strips threads and creates leaks
- Draining a hot engine – causes burns and improves drainage minimally
- Skipping the oil filter replacement – old filters trap contaminants and reduce lubrication
- Checking oil level on a tilted surface – gives inaccurate readings
- Forgetting to reinstall the filler cap – allows dirt into the engine
How Often Should You Change Oil?
Briggs and Stratton recommends changing oil every 50–100 operating hours or at least once per season, whichever comes first. For typical residential use (1–2 hours per week), this translates to once per season (spring before use, or fall after the last mowing). Keep a maintenance log to track oil changes and other service intervals.
Frequently Asked Questions
Can I use synthetic oil in my Briggs and Stratton mower?
Yes, synthetic oil is compatible with Briggs and Stratton engines and offers improved protection at extreme temperatures and extended oil change intervals (up to 200 operating hours). However, it is more expensive than conventional oil. Always use the correct SAE grade (SAE 30 or 10W-30) recommended in your manual, regardless of whether it’s synthetic or conventional.
What should I do if my mower is leaking oil after an oil change?
Stop using the mower immediately and check the following: (1) Is the drain plug tight? Loosen and retighten it firmly. (2) Is the oil filter secure? If your model has one, ensure it’s hand-tight plus three-quarter turn. (3) Is the filler cap installed? A loose cap allows oil to splash out. (4) Have you overfilled? Check the dipstick and drain excess oil if necessary. If leaks persist, the drain plug threads may be stripped—consult a local dealer.
Why is my lawn mower smoking after an oil change?
Smoking usually indicates overfilled oil. Excess oil enters the combustion chamber and burns, creating blue smoke. Turn off the engine, let it cool, and check the dipstick. Drain oil until the level reaches the maximum mark (not above). Run the engine again to see if smoking stops. If it continues, the oil may have spilled onto the exterior of the engine block during refilling—let the engine run for a few minutes at low idle for the excess to burn off.
Can I mix different oil brands?
Yes, mixing brands is acceptable as long as they are the same SAE grade (e.g., SAE 30 with SAE 30). However, it’s best practice to drain and replace all oil during an oil change rather than topping off with a different brand, which can affect performance. Always use the correct grade specified in your manual.
