Old oil settled out and looked clear like new oil - Sign of low quality oil?

OK, another oil question. I bought some STP high mileage 10W40 for the lawn mower over at my GF’s place. I would normally buy a diesel rated oil for a mower but this was what was available quick when I wanted to change it. I ran the oil all summer and changed it at the end of the season. I ran the mower for a few minutes just to warm it up and then drained it into a pan. It was one of those clear plastic containers that a gallon or so of salad comes in. The oil oil was nasty black and you couldn’t see through it. I set it out of the way in a shed over at her place and forgot about it for a while.

Just recently I remembered and took an empty oil bottle to collect the oil for recycling. It had been sitting in that salad container undisturbed for quite a while. All the dirt had settled to the bottom of the pan and the top oil was clear and lighter in color than most honey. It didn’t look dirty at all but there was a nice layer of sludge at the bottom of the pan. I poured off the clear oil and then had to basically scrape the sludge off the bottom of the pan.

I never really got the feeling this was very good oil even though it claims to meet all the modern specs and be a detergent oil. It would smoke and stink if you bogged the engine at all, especially on hot days. The oil that was in the engine previous was unknown but never did this. The oil that I replaced it with was a Rotella 10W40 and it doesn’t do this. Should oil settle out like this with modern detergent package? There is still a small amount of this oil in the original container if anyone wants more information. The bottle is red in color but that is all I remember besides it being a high mileage STP 10W40. I get the feeling I should use the rest of this as chain bar oil but not in an engine.

Any opinions about this?

This is one of those old flat tappet L-head type engines so the reason for the slightly thicker viscosity selection.

Always put the oil the manufacturer recommands and nothing else.

I’d guess the oil carried all the nasty bits in solution out of the engine. When it was allowed to sit awhile, the nasty bits settled out of solution into the pan.

My oil drain jugs (old clear windshield washer bottles) do similar things although not so dramatic.

I’d qualify that to say the type/weight/grade and API of oil the manufacturer recommends. I know manufacturers say to use THEIR oil. Which is total bull. GM, Toyota, Ford…etc…etc don’t make oil. It’s made for them by one of the oil companies.

Yup. You should get the correct oil and change it again.

I think the oil did its job. Detergent oil holds the carbon particles in suspension. That is why the oil came out black when you drained it from the mower. After the oil was drained and sat in the bottle, the particles settled to the bottom of the bottle. I don’t think there is any problem with the oil you used. You were wise to change the oil at the end of the season. Otherwise, the particles would have settled to the bottom of the crankcase. Unfortunately, I didn’t take my own advice. I was still mulching leaves in early December. It then turned cold and I just pushed the mower to the back of the shed.


I run Rotella oil in a lot of my equipment and have never seen it separate like this. I run the 5W40 in almost all my OHV stuff. This seems to be the “universal” power equipment oil over at Bobistheoilguy.com and I would agree it is a good oil for the job. It has brought several neglected “smokers” that burned quite a bit of oil back to life. Several that were burning quite a bit now don’t require any additional oil between changes.

I certainly wasn’t impressed with the STP product. I never liked the fact it smoked and stunk so bad at times. I don’t know the history on the mower so just figured it was getting old but it hasn’t been doing this since changing to the Rotella. The oil oil was as black as coal and then settled out clear??? This tells me it was definitely time for a change as it was no longer holding dirt in suspension.

I have never paid much attention to the brand of.oil I use in any engine as long as the oil is the viscosity specified by the manufacturer of the engine. That being said, I did switch my 25 year old mower from straight weight heavy detergent 30 weight to 10W-30 full synthetic oil and for two seasons it drastically reduced oil consumption and the smoking. However, at the end of this season, it began using more oil and smoking a little bit. I would go for a.short block, but other parts are no longer available for the mower including the blades. I hate to give up the mower because it has a cast aluminium deck which won’t rust and the product safety commission doesn’t allow mowers to be manufactured with aluminium decks because if the mower strikes a rock, if might cause the deck to shatter.

I’m going to guess the oil of the OP’s that separated has been sitting for a very long time.

It was changed on the last or second to last use of the mower this season. Then it got cold and the grass stopped growing. So, the oil has been sitting in that clear pan for a while and my GF wanted me to get it out of there so I brought some empty oil bottles over to collect it for recycling. I don’t have exact dates but would assume it was in late Aug or early Sept.

I hate that when a perfectly good product has to be junked because it is no longer supported with repair parts. You can sometimes find good used parts on eBay. I deal with this in my job all the time but with electronics. Apple is the worst and expect you to replace your phone every 3 years by dropping support for anything 3 generations old when the latest and greatest is released.

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I had some old quarts of oil unopened I decided to use up, there was sediment in the bottom of those jugs!

@cwatkin I agree that having to junk a machine or electronic item because a part isn’t available is bad. My parents went through the great depression and their values rubbed off on me. Our range and dishwasher are almost 29 years old. The refrigerator is 23 years old and our wash machine has served us for 26 years. A year ago, the washing machine developed a bad vibration and moved around the floor. Mrs. Triedaq hates to go shopping, so I called a repairman, figuring I would be out $60 for him to pronounce it dead. However, he replaced a shaft bearing without removing the machine from the house. My bill was $275 . I have gotten another year of service, and hope to get more and I didn’t have to hear Mrs, Triedaq squawk about having to go shopping. We had a clothes dryer that was in our previous house when I bought the property. It worked, so we moved it to our new house. Mrs. Triedaq was in the hospital when the latch mechanism broke. The only way the dryer would operate is if I wedged a chair between the dryer door and the wall. I found that parts were no longer available. However, I was buying groceries and just happened to go past the hardware section of the grocery store. I picked up a barrel bolt latch for a couple of dollars and attached it to the machine with sheet metal screws. It worked perfectly. I figured Mrs. Triedaq would want a new dryer, but her response was “Why replace something that works?”.We used that dryer for 2 more years. We are still using a Eureka upright vacuum cleaner I bought in 1977. Fortunately, I can still get bags and belts for the machine even at Wal-Mart. I just can’t get into this throwaway mentality of today’s generation.


Smart lady.

Just last month I finally replaced a TV that I bought in 1976. It finally died completely. Normally over time the cathode in the CRT erodes and the electron beam becomes unfocused, creating a fuzzy picture, but this one’s picture was still pretty good. It died healthy.

I tend to have the same approach to my car. To me it makes more sense to keep an old car running as long as it’s safe or can be repaired. Of course cars have the disadvantage of being exposed to the worse of the environment, and it’s true that new cars have additional safety systems (many of which I think are overrated), but new cars also have designed-in systems that I don’t like. Ones that take control away from the driver, and others that force the driver to take his/her focus off the road just to change the heater ductwork settings (for example).

While I certainly do rescue old vacuum cleaners, and wring the last bit of life out of them, I do not do that with washers, dryers or ranges. Newer washers use much less energy and water, never dryers are much more energy efficient and newer stoves are, too. Paying $275 to fix a 20 year old washer is just false economy in my view.

In many ways the same is true of cars and trucks. Sure, a 25 year old pickup that you use for dump runs and short hauls to the hardware or feed store can be fine, but if you drive it regularly you are using a lot of fuel and pumping a lot of pollution into the air. And the safety features of a new vehicle are nothing to dismiss as overrated. They work.

About the oil. Lubricating oil is supposed to pick up grit and foreign materials and carry them away from the moving parts, and most of it is used in vehicles that have oil filters that pick it out of the circulating oil. The oil has to pick it up and it has to let it go in the filter. When you put that sort of oil in a machine like a mower, with no oil filter, the junk in the oil just goes around and around. If the oil drops it in the crankcase when you stop, and leaves it there, that’s better for the engine. Just remember to start the engine and run it a while before you change the oil, so the gunk will get stirred up some and maybe come out with the drain oil.

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I wish I could find an old range to do it with.
My range is very old, I know not how old. The control for one of the large burners (electric) went out.
I went to the owner’s manual and looked up the part number. Couldn’t find a replacement.
Went to the manufacturer’s website; the part was discontinued many years ago and no suggested replacement exists. Called them to no avail.
Went to a heavy appliance repair store. Nothing.
Searched the internet. Nothing.

The one used in newer ranges is electrically and mechanically the same EXCEPT for the shaft diameter… and it won’t fit I COULD drill the panel hole larger, but then there exists no matching knob to fit (I checked).

I removed the old one and took it to parts suppliers small and large. Nobody could offer a replacement. An appliance repair shop on Hanover Street in Manchester tried really hard to find one for me… without success.

If I ever see an old range with the old knobs & switch, well, that’s what I carry tools in my car for! Meanwhile, I left the knob off so nobody (me) would try to use that burner. Don’t want to burn the house down.

I’m too stubborn to buy a new range. With the exception of that burner, mine works perfectly!

I have an old truck that is a gas hog. It is a beater but reliable after I fixed just about everything that could go wrong with it. It is mainly for short trips and to haul firewood on my property. It hauls scrap to the yard and such so is perfect for what I do with it. It is reliable enough for cross country runs but I certainly wouldn’t want to pay for the fuel.

With electronics, old equipment can become a security vulnerability because of lack of support. If a bug isn’t patched the device will become a liability if any important information is stored on it. Also, many newer cable/satellite units as well as DVD/Blu Ray no longer interface with the old analog TVs. The stuff may work as well as when it was new but is no longer supported. The newer TVs are more efficient on a per-inch basis but new TVs are getting HUGE if you ask me. I recently bought a new 55 inch when the few year old 45 died and thought I was getting a big TV. I read the reviews and they consider it a medium TV. Consumers seem to want bigger and more complicated which isn’t always good. I could have lived without all the smart features but the only non-smart TV’s these days were made as cheap as they come and got poor reviews on picture quality, etc.

Cars are getting the same way. I don’t like the touch interfaces and such that are so integrated into all the systems of the car. I suspect this will be the main killer of modern autos and not the engines and transmissions failing. I mean it can cost THOUSANDS to pull the dash and replace these systems. Many cars will probably be driven without a working climate control system, radio, etc. rather than be fixed, then sold at scrap prices.

Most riding mowers have an oil filter and a pressurized lube system these days but this was just a push mower without a filter so all the gunk just stays in the oil. Mowers live such a hard life with the high heat, loads, and dirty environment so changing the oil is even more important if you ask me. Sometimes it amazes me the abuse that some of these small engines put up with and keep going. Other times it is nuts at how one given pretty good TLC just flies apart. I had a basic Briggs single cylinder riding mower engine come flying apart at idle just after I slowed it down from mowing under load. There were no clunks or signs, just a bang and the sound of breaking metal as it came to a stop. I took it apart and it hadn’t thrown a rod. That was all still intact. The counterweight assembly was held on to the crank by flimsy aluminum brackets that busted and caused the failure. I looked this up and it was a known problem on certain engines. I got the engine used but you could tell it was cared for as the insides were shiny and clean without sludge deposits.

I checked to see what the new oil in this mower was. The container is over at my GF’s place with some oil in it. It is the Rotella T6 5W40 full synthetic in the blue bottle. I only ran this one or twice after I changed it but the mower seemed like a totally different unit. No smoke, no stink, and no oil consumption…

@wentwest. I know new appliances are more energy efficient, but I doubt that I could save enough water to pay for a new machine. I admit that I took a chance spending $275 to repair an old machine, but I’ve gotten another year of service so if the machine quits tomorrow, I still got my money’s worth out of the repair. I don’t know if it is true or not, but I have heard that energy saving appliances don’t have the life expectancy of older appliances. My son has been through three washing machines in the last 16 years. Both my brother and my son have had problems with their energy saving refrigerators that are less than 10 years old while my 22 year old box has never had a problem.
I bought a battery powered Black and Decker mower from a friend a couple three years ago. I had to replace the batteries at the beginning of the season two years ago. The batteries gave out this season so it was back to my old gasoline mower. For the $65 I paid for replacement batteries, I can buy a lot of gasoline for the old mower.
I am all for energy saving when it is economical for me. I replaced a 24 year old furnace that was still working but the company had gone out of business and I was worried about getting parts. It was a high efficiency furnace for its day. The new furnace is even more efficient. The furnace is in an attached garage. With the old furnace, there was enough heat in the garage for me to work there in cold weather. With the new furnace, the garage runs ten degrees cooler because more heat goes into the house and our gas bill is significantly lower.
Our local electric company has made it feasible to do some energy saving measures. At the church I attend, the electric company gave us $6 for each four foot fluorescent tube we replaced with a LED tube. I bought new LED tubes for $6.99 apiece. These LED tubes use less than half the energy of the fluorescent tubes. I rewired the fixtures and replaced 108 bulbs. The $108 cost will be made up in energy savings. However, I don’t think replacing my old appliances in my house before they hand in their resignations would be economically feasible. Of course, I’ll make sure the new appliances are energy saving.

I was told years ago when I still used Pennzoil that the reason it left the engine so dirty inside was that it did not keep the particles in suspension like some oils but would drop them out to collect on the engine parts. I don’t know but since switching to Mobil and Rotella, I have never had the the same issues on any engine I opened up. I wouldn’t be happy with an oil that dropped the sludge and everything into the oil pan. When you change oil regularly, you expect the engine to be clean inside.