I hope one of our resident small engine experts can explain this. Before starting the engine I check the oil and find it low. I add enough to bring it up to the full mark. After running the engine awhile I check it again and find the level way above the full mark. What's going on here?

If it matters, this particular engine is a 12hp B & S, but I've seen this on other engines too.

Maybe the oil is expanding some when it gets warm? Wouldnt seem it would expand all that much though.

I have a 12hr B & S on my mower. To check the oil, I must loosen the oil check stick and let it set a few seconds. Then I can check it. Must build up some pressure that forces the oil up.

It goes up the stick and stays a long time after running, wipe it off and read by just dropping the stick in,don't screw down.
Shouldn't hold over a quart at the very most from empty. 30 weight. I miss read the manual on my 5000 dollar zero turn I bought in 09 and after 220 hours,the engine suffered a oil related failure on a hot day.I used 10-30 and that is what I read in the manual. A reread with good glasses showed me in small letters,Synthetic only. Otherwise 30 weight. Thankfully I was able to refurbish the engine myself for about 250 in parts.

Harry,if your engine is building pressure,you may want to check the crankcase ventilation on the valve cover if it is a L head.If overhead valve,you may have a head gasket leaking that will only get worse and cause the engine to smoke and eventually ruin.

I got a serious beef with B&S and their infernal dip sticks. You pour any oil down that tube and you may as well wait until tomorrow to get a good reading. The oil sticks to the inside of the tube and the dip stick is pretty much designed to scrape oil off the sides of the tube on its way in. I check and wipe it off, check and wipe it off, check and wipe it off, etc. Probably what I'm doing is getting it all scraped off the inside then finally getting a good measurement.

Does the owner's manual specify the correct oil amount? If yes, why not drain out all the old oil, measure out the correct amount of new oil, pour it in, and stop using the dipstick?

This B&S dipstick thing has been an aggravation for decades.
Thirty years ago I discussed this with a Briggs zone rep.
He pretty much told me there was nothing that were going to do about it.
And,obviously they haven't.

Mark,

I'd hate to drain and refill every time I went to cut grass. That is how often I check my oil. I usually have to add a little each time.

need a pic of that engine if possible.

Well,I do know this can be done on the older 7 thru 12 hp vertical engines.
You remove the dipstick and rubber grommet in the crankcase and get a screw in oil plug from a old push mower or something briggs.The plastic 1 with 2 1/4 inch round thingys on it.Screw that in. When you check the oil look for it to be at the top of the hole.If it aint at the top,add until it is. I know this can be done because it is my solution to the problem.

My real gripe is those pull and twist oil drains that briggs and others are using to make it "easy" to change oil! You pull,and the whole #&## thing comes off and oil goes everywhere but in the oil drain pan.And manufacturers do not account for changing the oil in their designs, they spec a engine, install it on their machines and you have to figure out how to get the oil out without having a Valdeeze type situation on your hands. Case in point,Yazoo Keys zero turn with a Kohler courage engine.Junk engine by the way.

Like Hal Davis, I always check the oil level in the mower before I cut the grass.

When I change the oil on my Toro with a B&S engine, I have found that when put in the exact amount of oil as listed in the owners manual, the level only comes up to the bottom of the hashmarks on the dipstick.

I couple years ago when I was the small engine shop getting a new blade, a guy comes in with a mower and says it no longer runs. The mechanic checked the oil level and there was barely any in the mower. He told the guy he most likely scored the cylinder and rendered it into a piece of junk.

I made a comment to the customer that he should have checked the oil level prior to each mowing session. He gave me a puzzled look and said that he shouldn't need to check the oil because he always changed it every fall before he put it away for the winter, just as the owners manual prescribed…..

Perhaps it's too full and the oil is getting whipped up enough to make it seem fuller.

Does it go back down after sitting for a while (settling)?

O.T....but...........

I bought a brand new GMC pickup back in 1977, first new vehicle in my life. It was cursed with a number of manufacturing faults that quickly turned it into a regrettable purchase for years afterwards.

One of it's "best" tricks was to show a quart low on the dipstick. I carefully added oil and verified it was on the "full" mark. After driving a bit and checking again, it was one quart OVER full. I had this happen too many times to be a coincidence.

The only thing I can figure was a casting flaw in one of the heads of that 350, so that it held excess oil, allowing it to slowly drain. This would result in the goofy readings.

I now drive a Ford pickup.....

I've wondered if the counterweights on the crankshaft being down would make the oil level measure higher. Or would they (the weights) normally go deep enough to make that difference.

OT-anybody ever make a clear plexiglass side plate so you could see what goes on inside when the engine is running.

I stared at the little screw that held the plastic dipstick assy on the Briggs block of my last mower. Take it off. Take it off and throw it away Duane.
Those dipstick tubes diameters are a bit small and collect oil when running until opening, kinda like a savings bond. ;-) And they leak around the o-ring on the bottom.
Then thought IF I'm LOOKING for an old style plug like Mack describes. I'll never find one. I have to be looking for something ELSE to find what I wanted in the first place!
The mower I have now has a decent 20 horse Kohler single on it. Nice dipstick BTW. :-)
Due to EPA regs in the 90's Kohler lost out on their very good opposed twin engines they built and switched to the vee twins and those sure do have their limitations. Babbling stopped.

(Message edited by duey_c on May 15, 2018)

Stick with the Command series Kohler,any other name like Courage,challenger,NOPE.
The courage has improved but had a rash of problems the first few years of it's use.
Some Kohler and briggs models are the exact same as the Chinese copies of the Honda,beware of that.A different shape on the gas tank or air filter,but basically the exact same engine.Alot of Kohler dealers only stock 1 of that model because they are required to to fulfill dealer requirements.They hate selling them.
Duey,I might can mail you a plug if you need 1.
Steve photo the engine we can see,I will be glad to send you a plug to.

I let a friend borrow a pushmower and when he brought it back he said he was sorry that he'd blown it up, but it wasn't all his fault. How? I asked. He said it was 2 quarts low on oil. I drained it and it was fine. I guess he didn't pay attention to the dipstick and filled it to the top like the old motors.

Haha! Mack, send mine to Steve! That POS MTD is long gone. :-) Now I have another with a Kohler... I have a wrecked 3.5 horse out in one shop if I need one of the plugs. I think. ;-)
IF I can find it! I've long since lost a 24 T block out there.
Corey, you tripped a memory switch in my head! 35 years or so ago (I was sooo blinking young), I heard the story of a Perkins 4.236 at my work being filled completely to the oil cap in the valve cover by a local farmer. He was simply asked to fill it with oil... Takes all kinds, I guess.

In 1987 I bought a New Massey Ferguson 240 tractor with a 3 cylinder perkins Diesel engine.The owners manuel said to check the power steering oil level Daily when the tractor is new.indicating it could use oil and would need to be topped off, my crankcase oil level went up over the full mark in correlation to the power steering oil level going down, I was concerned about the power steering oil diluting the engine oil,but after the tractor had about 40hrs on it the consumption stopped and the engine oil level didn't increase, In retrospect I guess it took time for the P.S. engine seal to seat properly, They didn't tell You that.

Corey,

Back when I was in high school, my girlfriend's Mom asked to borrow her son's car. He said OK, but check the oil before you leave. Guess she was used to only checking the oil in the lawn mower (Back in the days before lawn mower dip sticks). She poured every quart of oil she could find in their storage room into his engine and it still didn't fill it up.......

Well, the cap said "Oil Fill"!

Is it a three dip or four dip Briggs & Stratton?

I have a number of Honda and brigs four cycle yard tools. Interesting my 95 Ford Aerostar power steering dip stick is marked both sides one for cold checking the other for hot checking. Long story short on any dip stick I check several times wiping the stick dry each time between checks because the stick often picks up oil from the sides of the tube its inserted into showing an incorrect reading. By doing that I have seen oil levels that barely show on the tip of the stick---not good!
Interesting story Jim Davis---I have a 205 Massey with the same engine and the same issue. Its a bullet prof tractor with over 10K hard hours. I finally put a bottle of power steering oil leak in with a large improvement in the system.

Hah! Proof positive about Briggs' dipsticks. See in a day or so.
Just bought an old (1998-2001 or so) self propelled MN assembled 21" mower with a Briggs 6 horse that smokes just a scosche on starting and has a slight rod knock (you should hear a couple of my T's!). Three carb primes and one pull later? It runs like a champ. Kinda like a T. Done way worse for $50.
It was shut it off for about 5 minutes after a test, I go out to check the oil and it looks as if there's about 6 quarts of very dirty oil in it!
It'll look different tomorrow.
Oh crap. Maybe I need an old style oil plug after all so I can toss that stick. We'll see.
:-)
Perkins-Shibaura 103-06 or 07 3 cylinder engines? Top notch engines! Cold blooded little devils. :-)

(Message edited by duey_c on May 17, 2018)

Do you see what you started Steve. .....????-

Oh Steve aint wound me up yet! Let me get started on those variable speed belts on Mtd riders! Those will make you cuss in foreign languages.

But Hey,Steve didn't ask what weight oil or brand!

I have an old Case riding mower with an Onan engine in it that does this... leave it set and the oil creeps 3" up the dipstick, I always have to wipe it off to get a real reading. That or my oil expands 3x when hot and contracts 3x when cold...

Mack, oh yes, you are correct! When one of those belts have a finger firmly pinched and trapped?
Mmmm, MN Onan power Jason. Two cylinder opposed I'd bet. Mmmm. Smooth. (say it in a velvety voice) :-)
Hah! The manual stated to tip the mower over to drain the oil out the fill/dipstick tube! There is a plug on the bottom but it's trapped by a belt retainer.
Don't know if it's a drain. Next time.
Ya Carl, you're right. :-) I'm thankful my mind isn't the only that wanders in thought. :-) Model T's and life experience go together? Hehehe!

I did some temper fits replacing belts or anything else below foot level on riders until spending about 75. on a harbor fright ATV lift.
For the amount of times the blades are sharpened or trash is blown out between the mower deck and mower frame its a great shop tool.

As to the Kohler engines: last I heard all the smaller ones were being manf. overseas. (this is quite old info though) + a Kohler tip; if your Kohler has hydraulic valve lifters be sure to use a multi grade oil in it. Straight 30wt, will lock the lifters up solid.