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Many months ago I mentioned that I haven't changed the oil in my 89 Ranger for years, and that when I did I would do a Blackstone test. The basic facts are the engine has just over 200k miles and has typically been driven once a week for 20 miles as preventative maintenance. It burns very little oil and has never needed oil added between changes, even back when I did go 5,000 miles between changes. The oil was last changed just over 3 years and 11 months ago, at just over 3,000 miles. The oil was Mobil 1 High Mileage 10W/40, the viscosity recommended for an 89 engine.

The results came in fine! Everything was relatively normal with the exception of copper being slightly high (11 vs. 8 normal) and Flashpoint being slightly low (370 rather than >385). Blackstone suggested going even longer next time!

Anyway, this has implications for other engines I own, such as generators that are not run much.
 

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I have never understood the 'time' aspect of oil life. Wouldn't containers be dated? Wouldn't it age in the bottle?, etc.
And what exactly is changing over time, evaporation?

Not saying it isn't a real thing. I just don't get it.
 
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I have never understood the 'time' aspect of oil life. Wouldn't containers be dated? Wouldn't it age in the bottle?, etc.
And what exactly is changing over time, evaporation?

Not saying it isn't a real thing. I just don't get it.
The main reason is because oil doesn’t start to oxidize, or “age” until it has been run through an engine and picked up contaminates that can change it’s chemistry. Fresh oil in a sealed container can stay good for decades.
 

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You get a certain amount of moisture in the crankcase during engine operation. Getting up to full temp for a period of time burns this off. If you ever owned a old rig, before the days of PCV's you would see a milkshake like buildup around oil fill hole and under the valve covers, very prominent in the winter time.
These new engines get to operating temp very quickly and I don't see any moisture buildup at all. I drive about 4K a year and oil appears as new after that time period. I still change oil.
 

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The reason there is a time stipulation from the manufacturer is for the reasons stated above; Contaminants that don't get burned off. The manufacturer assumes that if you don't hit the mile/usage-based limit for an oil change then the vehicle isn't being driven enough to get the oil up to temp and burn off the condensation, etc. It's not because the oil itself is the problem, it's the contamination that is likely to build up and lead to internal corrosion, etc.
 

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Yes, condensation is one problem. One year is a good round number and takes you though a winter. I'm going to guess that's where the year number came from.
But of course every vehicle is driven differently.
 

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I came across something that said oil degrades not only by miles but a shelf life of 8 mo . to 1 year There is a shelf life regardless of mileage
In the bottle? Maybe they were talking in the engine.
 

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Many months ago I mentioned that I haven't changed the oil in my 89 Ranger for years, and that when I did I would do a Blackstone test. The basic facts are the engine has just over 200k miles and has typically been driven once a week for 20 miles as preventative maintenance. It burns very little oil and has never needed oil added between changes, even back when I did go 5,000 miles between changes. The oil was last changed just over 3 years and 11 months ago, at just over 3,000 miles. The oil was Mobil 1 High Mileage 10W/40, the viscosity recommended for an 89 engine.

The results came in fine! Everything was relatively normal with the exception of copper being slightly high (11 vs. 8 normal) and Flashpoint being slightly low (370 rather than >385). Blackstone suggested going even longer next time!

Anyway, this has implications for other engines I own, such as generators that are not run much.
They would have to be tested to be sure. Those engines are way different.
I had a cheap mower for about 20 years a while back (Briggs engine). I never changed the oil and even had to add one time because it was starting to make funny noises. lol
That thing has been handed down a few times since and I bet it's still going.
I really should go change the oil in my Honda Tru Cut. That thing was exspensive.
 

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The main reason is because oil doesn’t start to oxidize, or “age” until it has been run through an engine and picked up contaminates that can change it’s chemistry. Fresh oil in a sealed container can stay good for decades.
I'm not 100% sure that is true. Many chemical compounds begin to breakdown or "de-combine" if you will, over time. I am not a chemist, but I would be interested in having one look at the specific compounds in a quart of oil (and many brands if possible) and give a report back on whether there is an degradation while sitting on a self for an extended period of time.

I would also speculate that this may be one more area where synthetic outshines conventional motor oil. We all know gasoline degrades fairly rapidly over time, and both gas and motor oil come from the same source, albeit significantly different refinery processes.
 

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I think Project Farm actually tested a can of unopened Quaker State from the 1940s or something...


Enjoy!
 

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I have never understood the 'time' aspect of oil life. Wouldn't containers be dated? Wouldn't it age in the bottle?, etc.
And what exactly is changing over time, evaporation?

Not saying it isn't a real thing. I just don't get it.
I have always been told that products of combustion that get past the rings, blow-by I’ve heard it called, actually creates an acidic condition in the oil. Then the oil does what you would expect an acid to do. I’ve had more than one person tell me that.
 

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I think Project Farm actually tested a can of unopened Quaker State from the 1940s or something...


Enjoy!
That's awesome! Oh the good ol' days when we opened oil with a can opener.
Damn I' old. :( lol
 

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That's awesome! Oh the good ol' days when we opened oil with a can opener.
Damn I' old. :( lol
But, do you remember the recycled oil that was in the glass bottles with the screw on steel spout ? I bought many of them as when I was driving my Ford Falcon the recycled oil was .25 a quart, of course gas was .24 cents a gallon and diesel was .17
 

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Saw that PF video on the ancient Quaker State oil. Oil's ability to protect certainly has come a long way in 70 years.

In other news, GM updated it's DIC programming, this takes effect after the powertrain warranty has expired. Don't push the extended oil change intervals too far 😄

Speedometer Odometer Gauge Trip computer Fuel gauge
 

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I have never understood the 'time' aspect of oil life. Wouldn't containers be dated? Wouldn't it age in the bottle?, etc.
And what exactly is changing over time, evaporation?

Not saying it isn't a real thing. I just don't get it.
Had an unopened plastic container of Mobil 1 (5w-30) in the rear door pocket of our 2007 extended cab Tacoma. I put it there (new) when we were leaving Houston just before Hurricane Ike hit in 2008. It stayed there (forgotten) until some time in 2021.
Decided to open it and see how it faired.
It looked bad, as in real bad. Didn’t stink, was not ‘gummy’, seemed to have the same viscosity but was very dark - darker than any coffee I’ve ever seen. Was going to take a sip to see if it tasted like coffee (I’m kidding).
Wish I’d had the presence of mind to have it tested, but into the used oil bin it went.

Being in the cab with high temp Texas summers I suspect it chemically decomposed over that timeframe - uncertain how much, or to what extent.
 
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I read an article a while back on synthetic oils. I recall it stated that synthetic oil has a 5 year shelf life if left sealed. Sealed meant the aluminum seals that are glued on after you twist off the cap. Some don't have it.
The article also stated that synthetic oil should not have more than one year in service life especially for low mileage vehicles. As time goes on I'm sure shelf life will increase with newer technology.
 

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But, do you remember the recycled oil that was in the glass bottles with the screw on steel spout ? I bought many of them as when I was driving my Ford Falcon the recycled oil was .25 a quart, of course gas was .24 cents a gallon and diesel was .17
I worked at a station at a lake that sold Golden West, it was refined used oil. sold it for 25 cents a quart and people thought that was high, we sold Trop-Artic for 37 cents a can.
Oh, we sold gas for 30 cents for regular and 36 cent for ethyl, now known as premium
in town it was 24 and 29 per gallon, but back then I bought a set of Brunswick tires at Otasco for less then 100 bucks
 
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