Technical Speaking of oil:) does it go stale/etc?

My neighbor across the street came over to my house last month and asked if I had any old oil. I had 2 gallons of drain oil out of my DD that gets changed at 7000 miles. She dumps a quart or so in her old Dodge pickup every few days and it seems happy.

 

This another scam like tire expiration dates?....

 

^^^^Really???^^^^

 

Do you have any old mechanical injector pump diesel engines in your stable?

Just add 25% gasoline to the oil and tip it in the fuel tank. [unused oil doesn't need cleaning]
It should make a little bit more power.

 

Careful, many don't understand sarcasm.

 

But only while wearing pantyhose, you forgot that part...

 

Meaning YOU!!!!! With your bulls..hit warnings.

 

What I was taught in auto shop class in the 70's is that oil does not wear out. However, it can get dirty through usage and become contaminated by use. The additives can break down over time, and react with other chemicals over time. It was common for many auto parts stores to filter and resell used oil for use in lower tolerance engines (older or worn out), or for general lubrication duties in oilcans. They blended it all together - single viscosity w/ multi-viscosity - no thoughts given to brands. It was just used oil, period. Grandad used to buy it in 5 gallon cans to lube his farming equipment, etc., or spray on the dirt garage floor and driveway to keep the dust down. It was cheap, available, and it worked.

 

Have a newer lawnmower with a Briggs engine and it has no provision to change the oil. There is a label that says to not change the oil, just check it and add if needed.

 

At your B&S headquarters….

“How can we sell more engines”?
Talk goes on for an hour or so then all of a sudden…

“I got a fuckin BRILLIANT idea…”

 

I have always followed Andy Granatelli' advice from They call me Mister 500 " any oil is better than no oil "

 

What brand of oil did the guy wash his greasy hands in on a TV commercial? Would have been the same timeframe.

 

I have known people with cars like that. If you have to add enough, it changes itself...

 

Worked in a gas station in Lompoc, CA around 69-70 and a Frantz salesman came in every couple of months or so driving a Pontiac with 4 Frantz filters on it. His sales pitch was that he never changed the oil, only the first filter at 3000 miles and added a quart of oil. In the two years I worked at that station, he claimed he had only changed the second filter once and never changed the 3rd and 4th. When you pulled the dip stick, his oil was just as clean as when it came out of the can.

 

There's some crude comments in this topic.

 

Glad you didn’t say “we’re gonna go down a slippery slope”

 

Crap I keep forgetting that part

 

Ok, confession time…

Ex son-in-law parked a OT suburban in front of my house. His dad gave it to him with expired plates and back fees. I am orange “gonna be towed soon” sticker on it. Crap. So was going to move it out in the back. Fired it up and oh my, rattled and knocked. Shut it off and had no indication of oil on the dipstick.
I wasn’t gonna waste new oil, so pulled out the oil change jug thing, filtered it through a funnel with with a pair of well worn briefs.
Sure did quiet it down.

 

You washed them first, I hope?

 

This one is like, as the say, a bad penny; it just keeps coming back around.

Besides contamination and additive depletion oil DOES wear out. All engine oil oxidizes over time; that is oxygen in the atmosphere attacks the base oil at the molecular level, causing a polymerization of the hydrocarbon molecules. The process is increased by the heat of operation (Arhenius Equation, the rate of a chemical reaction doubles for every 10c increase in temperature), and in the presence of catalyzing metals, like copper for instance. Once the oil becomes oxidized it is a non-reversible condition, it is "worn out".

The same process occurs with nitrogen, though at a slower process than oxidation, except in engines that have a lot of blow by. Nitrogen has a higher reaction temperature than oxygen, so when the oil is heated due to the heat of combustion gases nitration of the oil can occur.

Oxidation and Nitration of the oil causes it to darken in color and increase in viscosity. Due to heavier molecular weight some of the molecules drop out of suspension and form lacquers and varnish on the interior surfaces of the engine, and when it gets extreme they start forming sludge. The byproducts of oxidation and nitration are acidic and will attack the soft metals in the engine. You may be able to filter out some of the heavier weight molecules as they agglomerate into sludge, but you can't filter out the acids. New engine oil contains additives that neutralize the acids, and stop the reaction process; these additives are used up over time and eventually need to be replaced. The level of acid in the oil can be measured in an oil analysis lab; as well as the level of basic additives remaining.

The bottom line is, yes oil does wear out; the bit that it doesn't is an old wives tale, or urban legend, myth; one that is very hard to die. As many times as you try to put it to rest, it still comes back up. Always will I suppose, people want to believe something, so they just keep believing it no matter what.

 

I wonder how fast oxidation occurs when the oil is in a sealed can, vs when it's in a running engine? Perhaps 10 years of storage causes a similar amount of degradation, as driving 20 miles? or 200 miles? or 2000 miles?

The answer to this question kind of is the basic answer to the original question.

 

So, it burns away. Sorry to oversimplify, just sayin. Seems like everything mentioned save a couple, maybe, are all elements of combustuon in one or more forms and the leftovers they impart.

 

As mentioned above, the original question was whether the oil degrades substantially when it just sits and is affected only by time/gravity/and the atmosphere.
I think that when placed in any engine oil is going to degrade as it is affected by not only the factors above, but possible temperature extremes, and combustion by-products. I believe most of us would agree with that.
Lets look at another type of oil/fluid that doesn't get exposed to combustion by-products. Maybe this isn't a good comparison for some technical reason I am unaware of, but here goes. How long does the fluid in a car's automatic transmission last? There are manufacturer recommendations on replacing the trans fluid and filter, but how many people actually abide by them. I would guess that most people never change their trans fluid or filter in their cars unless they eventually have a problem.
Many vehicles go 10-20 years and 150K/200K and never have the fluid changed. Now as mentioned, this fluid is not subjected to combustion contamination. It also does not just set normally. On the other hand many of us have purchased an old car that had been parked for years and once we got the engine started, the trans worked just fine after setting . I have even drained some transmissions and the oil looked great. Some however will get overloaded and abused and burn the clutches and bands and the fluid will get contaminated. The point here though is that except when contaminated with some type of residue.........it seems to endure just fine. I do agree that eventually any fluid being used in a mechanical system will eventually need replacement....but usually because it is contaminated from some factor. Without the induced outside contamination from combustion this fluid really lasts way longer than 7 years.

A question which comes to mind is related to the over the road diesels. Now there is a place where mileage and combustion play a major part in oil life. I have no idea how these trucks are maintained. Can anyone enlighten me as to how long the intervals are between changing oil and transmission fluids in tractor trailer rigs........and do those professional drivers normally follow those guidelines?

 

I think something that plays a huge part is fuel quality in an engine .
Dirty contaminants in fuel become an addition to the oil eventually .
Sludge and varnish buildup are also a by product of dirty fuel .

Engines that run on CNG are almost perfectly clean inside ,,,I’m assuming the oil is much cleaner as well.
I’ve never changed the oil in one,,,,but I’ve seen several inside after tear down ,,,,,pretty darn clean .

And,,,I’ve seen many engines that were run on premium fuel,,,,most looked really good.
Many that were run on plain regular were nasty many times ,,,,,was it the oil change schedule,,,or a fuel quality issue ?
I’ve always wondered if that’s why regular grades of fuel are died red,,,,,to help hide the contamination and get rid of the foggy look .
Best grades of premium are always clear,,,,,,,here,, we all called it white gas
Back in the day,,,,it had a really sweet smell if you were traveling behind it .
Man,,I loved that ,,,,it was usually a hot rod machine burning it !

Back to the question,,,,,,I’m not an expert,,,,,high school diploma only .
Most of what I’ve learned,,,was from my old Daddy,,,,,,and later,,the expensive way,,,,,by not listening to what he told me,,,,lol .
I don’t really feel that oil,,,,,that is in a sealed container,,,,,,stored inside from heat and sunlight will deteriorate a great deal,,if any really .
Even racing fuel,,,,that is in a sealed drum ,,,,stored correctly,,,,,will last indefinitely .

The greatest threat to oil is heat,,,,,and exposure to the elements .
Oil is extremely old,,,( before our lifetimes ),,,,,in its base form .
However,,,after the refining process,,it is basically a brand new product and starts its life anew .
I’m confident that oil will remain in a usable condition for many years,,,even decades .

I keep all my stuff inside,,,in sealed containers,,away from the sunlight .
I’m certain it will outlast me ,,,,lol .

Even gear oil last for decades in use,,,,,as long as it isn’t contaminated by a foreign element .
Although,,,it does have EP,, ( extreme pressure) additives in it,,,,,and it does not operate at the high temps some oils see .

I don’t know,,,,maybe the oil temperature has a direct correlation to breakdown of the ingredients ?

Tommy

 

When I worked at a truck leasing company in the late '70's we changed oil and filters every 10,000 miles , these were mainly 350 hp Cummins engines .

 

I had a beater truck that burnt at least 5 quarts per 3000 miles. I'd fill it up with the oil I drained out my late model daily driver car, and race oil from street stip car. The drained oil was the color of honey. The truck burnt and leaked it all anyway.

You guys ever buy "filtered oil" locally recycled oil ? I've had older guys tell me about it, but it's time had passed by the time I had a vehicle.

 

When we got my 59 Chevy truck in 1977, I didn't have my drivers license, Dad drove it home ten miles. It burned a quart on the way home. There was half a case of Rev recycled motor oil in the cab. I don't remember what we did with that oil, though...

 

I see this as just another corporate CYA move generated by their legal team along with marketing, supported with enough techno-babble to suck us in. Expanding on this a bit, how about manual transmissions and rear axles? Drain plugs on many of these disappeared in the late '50s/'60s, with most manufacturers plainly stating that factory lubrication was for the 'life of the vehicle'. Rear ends with 200K+ miles on them outlasting the rest of the car are common. Many of the modern automatic transmissions are now 'lubricated for the life of the vehicle' also.

As to the assertion that heavier molecules will 'settle out' when standing, the 'mixing' that will go on as the lubricant is circulated in use I would assume redistribute them rather quickly. Sure, there may be an issue with 55 gallon drums (although I have my doubts) but I don't see this with sealed quart or gallon containers. It certainly wasn't an issue in the '70s when I worked for Chevron; we had multiple bulk dispensers for common-weight motor oils in unsealed containers.

And for all you guys who have bought into the 'tire expiration' thing, keep in mind that the same study that produced that was based on the worst-case scenario and only generated a 'recommendation' that is only semi-accurate if you live in the sunbelt. And in spite of the various antidotal stories circulating, the NHTSA also reviewed 3 years worth of accident reports from all the US states at the time and was unable to find even ONE documentable case of aged tires being a main factor in any accidents. Road hazards and underinflation were far and away the lead problems.

One could be truly cynical and think that this is an opportunity for the manufacturers to degrade the quality of their products to meet these lower expectations and generate more income...

 

The length of periods between service changed considerably over the 30 some years I ran over the road, always as a company driver. I never wanted to own a truck and have to deal with the costs associated with them. When I first started driving in the mid 80s, oil changes were done at around 10,000 miles. That was extended to 15,000 in the early 90s and somewhere around the time I quit driving in 2017, the company I was working for had extended the service to over 30,000 miles. There were significant changes in oils and fuel systems over the time frame in which I drove which contributed to service life. I'm sure that @BamaMav could chime in here with facts and figures since he has just recently retired from the road.