Synthetic oil question about length of time not miles

[Patman]

Most cars with an oil life monitor will have you go way past a year. For my Chevy, driving 5k miles per year, the OLM says to change the oil around two years.

That is started to change though, my C6 Corvette did not have a time factor so I could go two years and it would be around 10% oil life by then. But my C7 Corvette has a time factor so even if I didn't drive it at all the OLM would still count down to zero at the 12 month mark. A lot of guys who drive low mileage are very surprised at the first time they noticed that happen and they would only have 1-2k on the oil.

 

[SevenBizzos]

Oil age doesn't seem to matter

I stumbled across this article describing how Blackstone tested old(er), low mileage oil and determined that miles matter way more than time. https://www.thedrive.com/news/motor-oil-age-doesnt-matter-as-much-as-mileage-study Anyway, what other forum would I link it? Now argue!

bobistheoilguy.com

 

[belbers9715]

Oil age doesn't seem to matter

I stumbled across this article describing how Blackstone tested old(er), low mileage oil and determined that miles matter way more than time. https://www.thedrive.com/news/motor-oil-age-doesnt-matter-as-much-as-mileage-study Anyway, what other forum would I link it? Now argue!

bobistheoilguy.com

I would disagree that time does not matter. Oxidation happens due to oxygen being present in the atmosphere. Heat and pressure can surely speed up the process, but it will happen over time regardless. Engine oil pans are not in a vacuum. In addition, engines "breathe" with temperature changes. That alone means condensation in the engine from humidity over time. Only way to know is oil analysis, preferably with TBN/TAN measurement. I would also not use Blackstone due to how they handle measuring fuel dilution, but that's another discussion.

 

[Uncle Bob]

The referenced article is quite sketchy on several points. Note the recurring reference to 6 month intervals, when the guideline has been 12 months for decades now. The dichotomy of the very first & very last sentences sums it up: "...better safe than sorry" vs "...not throw away oil that's still the color of whiskey after 6 months." Car makers won't warranty oil related failures based on the oil's color.

 

[goingplacesanddoingstuff]

6 mo to 1 year if I lived in a high humidity place or did short trips. 2 years if I lived in a low humidity place and didn’t do as many short trips.

Seems like you’re probably in the latter category.

 

[kschachn]

The time issue (one year) with modern engines & oil changing is because as soon as the engine is started just one time following an oil change, a degradation process is started & doesn't cease. This is why onboard maintenance reminder systems use 1 year as a fixed pathway trigger for the service reminder indicator. This is especially important on GDI engines, as the soot created is especially harmful to certain parts like timing chains & components. I don't believe any car maker will honor a possible oil related failure without records of annual oil changes. I know the Euro makes will not. So, like many things, your particular conditions may work okay with skipping the yearly, but it will bite many.

It takes heat and the ongoing products of combustion to degrade the oil. Atmospheric moisture is relatively unimportant and would take a long time to be significant. Just sitting in the pan isn't going to introduce any more sulfur oxides nor soot. You need those sulfur compounds, water from combustion and heat to do much at all.

 

[NorthernDriver]

IIRC Blackstone just did a podcast where they tested used synthetic oil dating back to a decade. As in it sat in the pan of a car for a decade. It was still fine to use. I'll try and dig it up.

 

[NorthernDriver]

Here:

Motor Oil Age Doesn’t Matter as Much as Mileage: Study

An oil testing laboratory has found that the conventional wisdom of six-month oil changes might be a waste of your money.

www.thedrive.com

 

[John Galt]

Deleted

 

[subyski]

The reason for auto makers put a limit on time is to be conservative and trying to cover the whole population of drivers for all climates and to minimize their liability.

Miles and time in of itself doesn't tell the story. A vehicle having 2k miles in 1 year doesn't tell the story. Oil degrades the most from the actual combustion process, heat / cool cycles, and the "quality" of the cycle (think cold atm temps, length of driving to burn off moisture). The oil is going to degrade differently for 2k miles of 3 mile daily drives vs 4x 500 mile drives. How much? Who knows without running the actual experiment with the same vehicle in the same climate and doing comprehensive UOA's. Then it's going to come down to your own personal comfort.

 

[Uncle Bob]

It takes heat and the ongoing products of combustion to degrade the oil. Atmospheric moisture is relatively unimportant and would take a long time to be significant. Just sitting in the pan isn't going to introduce any more sulfur oxides nor soot. You need those sulfur compounds, water from combustion and heat to do much at al

 

[Uncle Bob]

Re GDI related soot in oil, our shop's factory trained Audi & BMW techs were taught it accelerates timing chain wear, when oil isn't changed yearly, regardless of mileage. One of our tech resources is an swri Automotive Research Lube Engineer with 3 decades of testing for oil & car makers. He tells us that soot aside, oil degradation by time, due to blow by & condensation, etc. does happen.
With respect to all here & Blackstone (we use them too, though not exclusively), even if we disagree that time alone is important, the fact remains, neither car makers nor independent warranties will cover failures that could be oil related, when their guidelines aren't documented. On older vehicles with no warranty, I could see have the oil tested & go from there, but being mindful if environmental or drive patterns change. Anything late enough to be GDI, I'd use spec oil & change guidelines.

 

[NO2]

Follow the OEM recommendations during the warranty period, then use 1 yr if you short trip or 2 yrs if you take longer (20-30 miles) trips on a regular basis. Change the oil at whatever mileage the OEM says to if its a GDI engine. This should not be that difficult and should cover all but the most extreme situations (like heavy towing)

 

[dubber09]

Imho, as oil degrades with use the contaminants accelerate its degradation thus time also plays its role.