Metal flake in oil from small engines

I am always a stickler for changing oil in anything that has oil. This ranges from simple single cylinder mower engines without an oil filter to car engines. I run synthetic in everything including the mowers.

This question mainly relates to small air-cooled engines without a filter. I know the oil essentially sits in the pan and gets splashed around the inside of the engine on these simple engines. Since there is no filter, any dirt or wear metals that get inside are continually splashed around the inside of the engine. If I get a new mower, I always change the oil after the first mowing and am amazed at the amount of metal flake in the oil. I am pretty routine in my oil changes until the metal flake goes away, then I change once or twice a season depending on how much it is used. We had a wet spring here so I changed my oil today. The mower had been run hard and bogged down in tall grass quite a bit so I figured it was due. It was starting to get dark on the stick but was far from being black.

I drained the oil into a pan and it was sunny outside. The oil had a nice sheen to it like you see in metallic flake paint. I added like half a fill of oil and removed the spark plug wire. I turned the engine over by hand for a minute and then drained this again. It didn’t look much different than the first oil I drained. I went ahead and refilled like normal and continued on from there.

The old oil wasn’t really dirty but definitely had lots of wear metals. This is something I have seen on many small engines and I am curious of standard engines with a filter generate the same amount but you don’t see it in the oil because the filter captures most of it. I know that these engines are probably made cheap and may not be made to the same standards as something in a car but was just curious. Also, how big of a deal are these particles? Are they small enough to pass through the bearings, etc. without causing much damage? Either way, I think engines are best with clean oil and no particles of any kind.

With aircooled VW engines, oil changes are key for that very reason. Some ACVW people put full flow oil systems on to improve that situation but that involves some modifications to the case, if you want to do that right.

So you mean that the old VW engines didn’t have a filter? I knew they were simple but don’t know a whole lot about them besides that. Was this on the first ones or all of them?

to the OP, you are using quite a bit of resources to keep your engine clear and clean. what you are doing is great for the engine, but might be a bit excessive from the “utilization” of resources. there is a line between too much and not enough.

for small engines that are not worth much, ie a lawnmower or snow blower, you are removing particles by flushing your oil. it isn’t necessary but not detrimental.

look at your neighbors that don’t have your attn to detail. plenty of people operate their mowers without an annual oil change and do it every 3 years and have plenty of life in their motors.

my 4.5 hp push mower has lasted 15 years without an oil change. i don’t feel that i am neglecting it, because it is just not that necessary. I add oil and it keeps running. I have never drained it, nor have I changed the spark plug. if it runs, why bother.

now if i spent 800 bucks on a riding mower, i would change my protocol. but my mtd mower was $70 new on clearance at Target and I just couldn’t pass it up.

All Aircooled VW engines - edit: let me restate that: the engines into the late 70’s did not have filters. They made bugs in Mexico up to about a decade ago. Not sure what those engines look like.
They had screens but those would let coffee grinds through so aren’t super effective. As such, you change the oil religiously at 3K. One does wash the screen off with mineral spirits, though. It helps but isn’t ideal.
There are bolt on solutions with spin on oil filters that mount instead of the oil pump cover but they are actually said to be more trouble than they are worth. Even when ‘full flowing’ a case by machining out the passages and tapping a spigot in to go to an oil cooler and filter, you have to be careful as air cooled engines are very picky when it comes to temperature. They like to run at a very specific temperature, not too cool and not too hot. The experts say that one can actually run too cool with a full flowed case, unless you drive aggressively and have a bit more than the standard engine.
Those engineers of old really knew their stuff, producing a solid design for very little money.
Just change the oil and adjust the valves periodically and you’re good to go.

@cwatkin–back in the old days, many cars didn’t have oil filters. My 1947 Pontiac did not have an oil filter. On the 1955 Pontiac I owned, the oil filter that year was an option and my Pontiac didn’t have that option. The engine had been overhauled by the dealer just before I bought the car, but I still had problems with sludge getting into the rocker arm studs and causing the rocker arms to chirp. I did buy the oil filter assembly from a wrecking yard and removed the block off plate and added the oil filter. My parents bought a new Rambler in 1960 and the oil filter was a dealer installed option. They had the oil filter installed, but it was the partial flow type so that most of the oil bypassed the filter.
On small engines, the instructions with my mower said to change the oil after the first 25 hours and then every 50 hours after that. In severe conditions, the oil is to be changed more often. On the 4 stroke rototiller that I owned when we had a community garden plot, I changed the oil about every 10 hours due to the dusty conditions. I think that following the manufacturers schedule for changing oil on a small engine is sufficient. Just as important is to keep the air filter serviced as the dirt sucked in through the air cleaner can be just as damaging as metallic flakes in the oil.

It’s great to change oil and hard to forget the metal flakes that are in it. I try not to care too much about some machine that seems to operate forever with die-cast aluminum parts. They just go and go unless they run low on oil.

Lol - @triedaq is right!. I have a 52 dodge truck. It has an oil ‘filter’ consisting of what looks like a bunch of wadded up athletic socks packed inside one large sock. It doesn’t do much other than make an unholy mess when you change it. It is a real pain replacing it because you have to roll the sock up in a thin sheet of sheetmetal, push that shebang into the filter housing and then pull the sheetmetal out. A major pita. Most owners just change oil frequently.
On my 64 rambler you can tell the oil filter must have been an option because it is mounted upside down, smack dab on the middle of the engine, right on top. Really weird looking and mess making.

Yeah, you may be right. Why spend the money to flush the oil with a full synthetic if the engines are so cheap to start with? I know lots of people who never change their mowers, even when they are new and all the break-in metals are in the oil. Some of these run forever but seem to become oil burners rather quickly. Others throw a rod in short order.

I have been given a couple of old mowers with oil that looked like tar. They were given to me as the carb had gotten gummed up and they didn’t want to drop the bowl and spray it with carb cleaner. This got the engines running but I had to change the oil. The new oil was so black after one mowing that I had to change it again. These old and neglected engines have thrown rods every time I have done this except for once. I swear that changing the oil on an engine that is very neglected and worn out may do more harm than good. I don’t know if the sludgy thick oil is cushioning bearings that are worn far out of spec or what but I have had it happen too many times to be a coincidence. Now, these engines are just about done anyway but the clean oil seems to hasten their demise.

I change my oil at least once per mowing season and sometimes more if we get lots of rain that causes the grass to grow a lot. Sure, I know that most push mowers are cheap crap but why not at least try to take care of them? I guess it is just in my nature not to treat everything as disposable. I know my engines outlast the decks but I can always find a good mower deck with a locked up or blown up engine out at the curb on trash day.

@RemcoW–If your 1964 Rambler was a 6 cylinder model, the oil filter was an option and it was a bypass filter. In 1965, the Rambler Classic came with a new 7 bearing engine with hydraulic tappets and the oil filter was standard. The conventional wisdom back in those days was that if an engine did not have hydraulic tappets as your 1964 Rambler did not, the oil filter wasn’t necessary. Also, the detergent oil was not required in these engines.
I would bet that your 1952 Dodge truck has a full flow oil filter. Chrysler began using these at an early date. I owned a 1948 Dodge and it had an oil filter. GM stayed away from oil filters under the assumption that an oil filter caused more chances of an oil leak.

I had a 64 Rambler Classic with the 196 six cylinder engine. It had a remote oil filter and a 7 main bearing engine with hydraulic lifters. I rebuilt that engine once.

Yup, it is a 196. A real speed monster. :slight_smile:
You’re also right on the dodge truck.

You know your vehicles!

Yeah, you may be right. Why spend the money to flush the oil with a full synthetic if the engines are so cheap to start with?

Running full synthetic in a lawn-mower or snow-blower is a no brainer. I’ve been using full synthetic in this type of engine for years. The cost is insignificant. You change the oil once or twice a year…that means it’s costing you $8 MORE per year…that’s CHEAP. …so why not??

Well first off, you don’t really have any bearing in there, unless it is really a commercial model. The piston rod has no bearings and just rides on the crank and piston pin. There is a bushing in the case but thats about it. If you open it up, you’ll find those gray gobs of metal particles in the corners and bottom. I’ve done it myself but all you are doing by flushing is removing that gunk that isn’t going anywhere anyway. Kinda like what you would find in the pan of an automatic trans when you change the fluid.

I’ve used the same 18" pushmower with a Tecumseh engine since 1988. I followed the manufacturer’s recommendation and have used heavy detergent 30 weight oil since the mower was new. The mower is now showing some signs of old age, so I may replace it this year when mowers go on sale. If I do replace the mower, I will try full synthetic. If this additional cost doesn’t double the life of the mower so that I can use it for 50 years, I’ll bill MikeInNH for the extra cost of the synthetic oil.

I feel that synthetic oil in an air-cooled engine is the way to go as the harsh and often hot conditions are way harder on oil than a liquid cooled engine which is much more of a “controlled” environment. Is the wear completely stopping? No, and this is obvious by the metal flake in the oil. Where is most of the wear in an engine like this coming from? I know that the cylinder bores in all but the commercial/pro models use some type of hardened aluminum alloy around the bore but that is it. I have pulled these engines apart and it is amazing they work as well as they do considering the conditions and maintenance that most get. The rod is cast aluminum and it just rides on the crankpin. Maybe they just don’t generate enough power to tear things up.

I bent a crank once hitting a rock. It was a decent mower and engine before this so I looked into the price of buying a new crank and replacing it. The crank was like the price of the mower! They once wanted like $100 for a gas tank. I found a junker in the trash with a similar engine and the gas tank was identical so that got put to good use.

On another note, I found a commercial grade mower in the trash one time. I forget the brand but it was either a Toro or a Snapper. It was red in color. The engine was a 5 hp Yamaha or Kawasaki (forget which) and looked like any other mower engine except that it used full pressurized lubrication but no filter. The carb was gummed up from sitting and all it took was a good cleaning to get it running well. I changed the oil and sold the thing. It was running like a top but didn’t have the power that the 7 HP Briggs I am currently running has for pushing through tall grass and weeds.

I use straight 30 weught in all my mowers because that is what the manufacturer recommends. The heat of an air cooled engine causes multi- viscosity oils to lose viscosity because the the additives that make a thin oil ,like say 5 weight, act like a 30 weight at high temps break down faster than the oil itself.
I have never thought of using synthetic and don’t know if it would work better than 30W so I guess I will stick with what I know works.
Still cutting grass every week with a 1978 International Harvester Cub 85 riding mower.

I never saw any “metal flake” in the oil of any of my SME stuff so I never went to any lengths to deal with this problem …This “problem”, I think, is largely imaginary…

I change oil in my mower once a season. This is the first time I’ve used synthetic in the mower and it seems to like it–it seems quieter than it did before. I’ve seen a few metal flakes, but figured this is normal for a tiny engine with a tiny crankcase and a small amount of oil. Your car does the same thing but the filter catches most of it, and there’s a lot more oil to hide it.

Re. mower engines though, all I can say is that if Briggs & Stratton made car engines, you’d probably keep the engine and replace the rest of the car every 20 years or so. Every Tecumseh engine I’ve had has been a pain in the butt to start when cold, though it’s off the subject.

I've used the same 18" pushmower with a Tecumseh engine since 1988

I have a Troy built mower I bought in 86 that’s still running strong and I don’t see replacing it any time soon. I use this to mow the lawns at a couple of Duplex’s I own.

My home mower has a 14hp Kawasaki engine. It’s now 15 years old…and still running like new. This is a more complicated mower since it has a pressurized oil system with a oil filter.

Will they last a lot longer then just using regular oil??? Not sure. But the cost is so minimal that I might as well. I do know that I don’t want to replace my home mower. That type of mower is very expensive ($2k+). The little 22" cut push mowers I can get for $200 almost anywhere.