How to drain oil from Briggs and Stratton lawn mower

Briggs and Stratton lawn mowers are one of the most reliable and popular brands around. As such these engines tend to last over 20 years if maintained properly.

How to drain oil from Briggs and Stratton lawn mower.

There are three ways to change the oil in your Briggs and Stratton lawn mower engine. Each has pros and cons which we will go over in detail.

  • Drain plug method.
  • Vacuum pump dipstick method.
  • Tilting the lawn mower over to drain the oil from the dipstick.

Make sure to heat up the engine oil first by running your lawnmower for 5-15 minutes. This will mix up any carbon and sludge contaminants in the oil and make it easy to drain.

In this post we will be showing you how to drain oil from a Briggs and Stratton lawn mower engine once a year or every 50 hours of use. This is to prevent carbon and sludge build-up in the engine.

Briggs and Stratton oil drain valve location

Briggs and Stratton oil drain valve location

Most Briggs and Stratton small engines will have an oil drain plug either on the bottom or the side of the engine depending on the model. Most of the time the lawn mower oil drain plug will be under the engine. You can find it by tipping the lawn mower on its side and locate the oil drain bolt.

Depending on the model and type of lawn mower you will either have a 3/8 socket drain plug, 7/16 square head, or 1/4 hex head Allen drain plug bolt.

Go ahead and warm up the lawn mower for a few minutes. Shut down the lawn mower and remove the spark plug lead for safety.

Tilt the lawn mower to one side and remove the drain plug. Place an oil pan under the lawnmower and tilt it back down to let the oil drain. I like to lift each wheel up with a few bricks to allow the oil drain pan to fit under the lawnmower.

Once all of the oil has been drained replace the drain plug and tighten it up. A new washer or o-ring will help prevent leaks.

How to change oil in lawn mower without a drain plug

How to change oil in lawn mower without drain plug

If your Briggs and Stratton has no oil drain plug like my lawnmower, then you will have to use a vacuum oil pump to pull out the oil from the dipstick tube.

The oil will flow better if it is warmed up so start the lawn mower for 5-10 minutes to heat up the oil.

how to drain oil from lawn mower
How to change oil in lawn mower without drain plug

I use this dipstick oil change pump with a small tube to drain the lawnmower engine oil. Once all of the oil is drained, you can top it up with some new 10W-40 or 10W-30 engine oil.

I love my oil drain vacuum pump as it gets used often to change the engine oil in my Jet Ski as well as my cars without removing the drain plug. Well worth the investment.

Lawn mower engine oil color after 1 year of use.
Change your lawnmower oil every year. New oil vs old oil.

As you can see from the above image the oil was extremely black, this was after 1 year of lawn mower use once a week. With heavy usage, you should change the oil every 6 months. I use Castrol Magnatec part synthetic engine oil. If it is good for my car it’s good for my 4-stroke lawnmower. Looks like I will start changing the oil every 6 months now.

Lawn mower recommended oil viscosity chart.
Lawn mower recommended oil viscosity chart.

If you are very fussy you could use fully synthetic engine oil. But let’s face it most lawnmowers do not have high-performance engines.

When was the last time you changed the oil in your lawn mower?

Briggs and Stratton lawn mower oil capacity

Briggs and Stratton have a huge variety of different size lawn mower engines. So for a standard size 375 small engine lawn mower the oil capacity is 0.65 us quarts or 0.6L, so buying a 1L/Quart of oil will do the job nicely.

Remember to check the level on the dipstick to get a true and accurate oil level.

Tilting the lawn mower over to drain the oil

Generally, it is not recommended to tilt a lawn mower over to drain the engine oil but it can be done. This is because upon startup the lawnmower will smoke for a few minutes while it burns off the spilled oil.

In 4-stroke engines, this engine oil is used to lubricate the piston, rings, bearings, valves, springs, camshafts, pushrods, and seals. When you tip a lawnmower over oil can tend to be trapped in various places. This can cause hard starting and blowing of smoke when running for a while.

To change the oil warm up the engine for 5-15 minutes and turn it off. Pull off the spark plug lead for safety.

Remove the oil filler cap and tilt the lawnmower over to drain the oil into a drain pan. Make sure the oil drain tube is on the low side and the exhaust muffler is on the high side. Be careful as the engine may be hot. It will be easy if you have someone else there to help you.

Once all of the engine oil has been drained you can pour in some 10-40 4-stroke engine oil. Be sure not to overfill the crank case and check on the dipstick for the correct level.

Briggs and Stratton blowing oil out carburetor

There are two main reasons your Briggs and Stratton is blowing oil out of the carburetor. You either have worn piston rings that are pressurizing the crankcase causing engine oil to pass up and through the carburetor. Or you have overfilled the engine crankcase with oil past the high level on the dipstick.

If you have worn piston rings then you most probably will have a hard time starting your lawn mower and it will be blowing smoke.

Having an overfilled crankcase with oil can be an easy fix of just draining some engine oil by using a vacuum pump or removing the small engine drain plug.

Briggs and Stratton blowing oil out exhaust

This can happen if you have tipped your lawnmower on its side to remove the oil out of the dipstick filler hole. Run it for a few minutes and it should clear up.

If your Briggs and Stratton are blowing oil out of the exhaust after every use then check that it is topped up to the correct level. You could also have worn piston rings.

Lawn mower blowing lots of smoke

Lawn mower blowing lots of smoke

If your lawnmower is blowing lots of smoke it could be because the engine oil is passing up into the combustion chamber. The piston rings could be worn.

Another reason is that the oil mixture in 2-stroke engines could be incorrect. Too much oil in the fuel mixture. Is it 25:1 or 100:1. You will need to read your owner’s manual.

Sometimes on startup if the lawnmower has been sitting for a while it will be smokey but it should hear up after a few minutes when it gets up to running temperature.


Hopefully, the above tips and tricks will help you to change and drain the oil from a Briggs and Stratton lawn mower. It really is easy and you will save yourself $100 by taking it to the lawnmower service center. You really can do your own 4-stroke lawnmower service it is easy and fun. Nothing hard about it.

I find that the easiest way is to use the oil drain vacuum pump. It is cleaner and faster.

Just remember to warm up your lawn mower first to aid in extraction and stir up all of the impurities into the oil. If you take care of your lawnmower it will last you over 20 years.

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