[fireprix]

I have a couple cases of Quaker State Deluxe 10W40 from the 80s or 90s unopened. Think it’s still any good?

[77 TRASHCAN]

I don't have a clue as to how motor oil goes bad. Geez, the additives ARE still in that container along with everything else!!!

Then there was a thread some time ago debating as to whether or not to fill your oil filter when changing oil. Another deal I don't understand the need for a debate!!!
The first place oil is pumped up is the filter!!!

Motor oil is NOT potato salad!!!

Skip, I've seen that fine sediment in quarts of "new" oil.

[77 TRASHCAN]

I don't have a clue as to how motor oil goes bad. Geez, the additives ARE still in that container along with everything else!!!

Then there was a thread some time ago debating as to whether or not to fill your oil filter when changing oil. Another deal I don't understand the need for a debate!!!
The first place oil is pumped up is the filter!!!

Motor oil is NOT potato salad!!!

Skip, I've seen that fine sediment in quarts of "new" oil.

[mgarblik]

No scientific proof of this. But I would offer that engine oil does not, to my knowledge have an expiration date on the outer cases or the individual boxes. Almost all major oil manufacturers have a "Lifetime" engine guarantee on the oil they sell. If say 10 year old oil was causing engine failures, someone would be crowing all over the internet about it and filing a law suit against the oil company. Strictly an opinion here, if the oil has been stored in a cool, dry place in a sealed container, it would be very low on my list of 100 things to worry about on my hobby car engine. FWIW.

[BILL BOWMAN1]

My rep says 5 years. But maybe that is to cover their butts. I know I’ve used oil way older than that, and on some of my low use vehicles, the oil is older than that in the pan.

[grandam1979]

Well I poured out one of the Mobil 1 quarts I don’t know if it’s supposed to have an orange tint to it but it does. Then cut the bottle in half it had a thicker than the actual oil coating on the bottles inside a little darker orange also. So a lot of the bottles have orange stains on the outside of the bottle I’m starting to think it was leaching through the bottle. I haven’t done it yet but will do the same with one that’s not stained and see what I find.

[Formulajones]

Originally Posted by BILL BOWMAN1

My rep says 5 years. But maybe that is to cover their butts. I know I’ve used oil way older than that, and on some of my low use vehicles, the oil is older than that in the pan.

Wow you have vehicles you haven't changed the oil in over 5 years?
Geeez

[besserspat]

Originally Posted by Formulajones

Wow you have vehicles you haven't changed the oil in over 5 years?
Geeez

Same here, some get barely moved around from my shop to the storage barn. In the last 12 years ...lol

[Formulajones]

Wow. Vehicles you still start and drive on occasion? That's what it sounded like Bill is doing. I'd love to see an oil analysis posted up on that, I've never left one in that long to even send in a sample, don't think I want to. Even the nomad which I parked in about 1990-ish still gets it's oil changed once a year. I start it up to move around only and maybe every 6 months I'll cruise it through the neighborhood just to exercise it.

[grandam1979]

Cut open a bottle that was not stained the oil is the same color but the bottle did not have the thick layer on the inside. If you’re looking for a great deal on oil stop and see me at Norwalk we will have two cases of BP for sale at a big discount.

[JSchmitz]

Originally Posted by Formulajones

Wow. Vehicles you still start and drive on occasion? That's what it sounded like Bill is doing. I'd love to see an oil analysis posted up on that, I've never left one in that long to even send in a sample, don't think I want to. Even the nomad which I parked in about 1990-ish still gets it's oil changed once a year. I start it up to move around only and maybe every 6 months I'll cruise it through the neighborhood just to exercise it.

My philosophy is also once a year regardless of miles. Oil is hygroscopic. The worst thing is setting. It accumulates water at the bottom. That water makes sludge. When you warm it up to operating temperature, it cooks the moisture out (my theory). Your exhaust will do a similar thing. If you just start it up for a short while it'll condense moisture in the mufflers and pipes. Gotta drive them!!! Rubber goes to he!! if it sits too.

[Formulas]

Oil isn't born with additives thats why they are added,

Be interesting to know the circumstances in which these additives are added IE the environment in which this magic takes place. Is this replicated at startup or run time.

Does the molecular structure of the additives break down and turn into another compound, Break down into basic elements? or do they just fall out of suspension

[misterp266]

Originally Posted by mgarblik

No scientific proof of this. But I would offer that engine oil does not, to my knowledge have an expiration date on the outer cases or the individual boxes. Almost all major oil manufacturers have a "Lifetime" engine guarantee on the oil they sell. If say 10 year old oil was causing engine failures, someone would be crowing all over the internet about it and filing a law suit against the oil company. Strictly an opinion here, if the oil has been stored in a cool, dry place in a sealed container, it would be very low on my list of 100 things to worry about on my hobby car engine. FWIW.

Agree. Just add a can of 20 year old STP and you’re good to go! 👍

[besserspat]

Originally Posted by Formulajones

Wow. Vehicles you still start and drive on occasion? That's what it sounded like Bill is doing. I'd love to see an oil analysis posted up on that, I've never left one in that long to even send in a sample, don't think I want to. Even the nomad which I parked in about 1990-ish still gets it's oil changed once a year. I start it up to move around only and maybe every 6 months I'll cruise it through the neighborhood just to exercise it.

Yeah I do similar, I dont start the car or motorcycle unless its going to run long enough to burn off all the moisture and condensation , drive em super gently and just in order to get the blood flowing so to speak.

If a car or motorcycle is being put back into regular street or racing duty , I obviously flush ALL the old fluids including brakes etc

Its fun to do that its like finding " barn finds" in your own barn... im my best customer.!

Peter

[JSchmitz]

Originally Posted by misterp266

Agree. Just add a can of 20 year old STP and you’re good to go! 👍

LOL!

I had a '55 Chevy Sedan Delivery. It had a 235 straight six, three on the tree, and factory 4:10 gears. That thing burned oil almost as fast as gas! I would buy the thickest oil I could find. I think it was straight 50w. Then I would pour in STP or Motor Honey (whichever was cheaper). Ran like a top though!

[Shiny]

Originally Posted by Formulas

Oil isn't born with additives thats why they are added,

Be interesting to know the circumstances in which these additives are added IE the environment in which this magic takes place. Is this replicated at startup or run time.

Does the molecular structure of the additives break down and turn into another compound, Break down into basic elements? or do they just fall out of suspension

I went looking for education on the chemical stability of motor oil and specifically, how the degradation depends on temperature.

I found more than I can ingest or understand, but this paper has a good discussion about all the different chemical mechanisms that can cause changes over time:

Link to Thermal Degradation Paper

More importantly, the results of accelerated testing at multiple temperatures allow the engineers to quantify the changes as a function of both time and temperature, which gives them tools for predicting life and comparing formulations. It won't substitute for real life testing but gives them some lab tools to understand what's happening in service.

At a high level, they report a thermal activation energy of about 0.9 eV for many combined effects. This is a high value in the world of this stuff, which means temperature is a HUGE influence on the chemical stability.

I used to do similar testing to predict product reliability. Clearly, nobody can wait for 10 years of testing before shipping a new product. Accelerated temperature testing is one common method to characterize chemical degradation as a basis for life predictions.

With this published data the "acceleration factor" (ratio of time at temperature for the same effect) between room temperature storage and 150C is ridiculously high, so by itself, isn't going to contribute to this debate.

I agree that a manufacturer's shelf life recommendation will be VERY conservative, but they are dealing with so much uncertainty about HOW and WHERE their product is stored, they won't take chances.

Another challenge for them and for us is guessing "how much change" is OK? All oils will start to degrade as soon as they go into the bottle. So how much change is allowed? How much change in viscosity is OK for you? What percentage loss of additives is OK? You all get the complexity....

Me - if I opened an old bottle and it was clear, I'd use it..maybe up to 20 years. If it was dark, smelled funny, or was cloudy, I wouldn't. And I would not run a steady diet of old oil. I'd either dilute it or alternate with new oil.

My 2 cents

Mike

[JSchmitz]

Originally Posted by Shiny

I went looking for education on the chemical stability of motor oil and specifically, how the degradation depends on temperature.

I found more than I can ingest or understand, but this paper has a good discussion about all the different chemical mechanisms that can cause changes over time:

Link to Thermal Degradation Paper

More importantly, the results of accelerated testing at multiple temperatures allow the engineers to quantify the changes as a function of both time and temperature, which gives them tools for predicting life and comparing formulations. It won't substitute for real life testing but gives them some lab tools to understand what's happening in service.

At a high level, they report a thermal activation energy of about 0.9 eV for many combined effects. This is a high value in the world of this stuff, which means temperature is a HUGE influence on the chemical stability.

I used to do similar testing to predict product reliability. Clearly, nobody can wait for 10 years of testing before shipping a new product. Accelerated temperature testing is one common method to characterize chemical degradation as a basis for life predictions.

With this published data the "acceleration factor" (ratio of time at temperature for the same effect) between room temperature storage and 150C is ridiculously high, so by itself, isn't going to contribute to this debate.

I agree that a manufacturer's shelf life recommendation will be VERY conservative, but they are dealing with so much uncertainty about HOW and WHERE their product is stored, they won't take chances.

Another challenge for them and for us is guessing "how much change" is OK? All oils will start to degrade as soon as they go into the bottle. So how much change is allowed? How much change in viscosity is OK for you? What percentage loss of additives is OK? You all get the complexity....

Me - if I opened an old bottle and it was clear, I'd use it..maybe up to 20 years. If it was dark, smelled funny, or was cloudy, I wouldn't. And I would not run a steady diet of old oil. I'd either dilute it or alternate with new oil.

My 2 cents

Mike

All very good points and information. It comes down to risk (due to uncertainty) vs. savings. It it worth betting your engine on some free old oil? I would evaluate it the same as you described.