Mileage, or time for OCI?

[Liquid22]

All,

Regarding oil change intervals, dealers/manufacturers will tell you to change your oil based on mileage OR time. As an example, 7000 miles OR 1 year is when you should change your oil.

My intuition leads me to believe that the mileage on an oil really determines when you should change it.

I guess what I am asking is your opinion on this matter. Any sort of evidence/experience would be greatly appreciated.

P.S. I tried searching for this matter and had no luck.

Much appreciated.

 

[mechanicx]

Actually without considering the time and driving cycle milage is sort of a poor idicator. What degrades an oil is when it's not at operating temperature and has to buffer acids from condensation, fuel enrichment, stop and go driving means more engine revolutions and more fuel. So an oil with 3K miles but 6 months of use may have had more degradation.

On the other hand an oil that has say 7500 miles/3 months may have had few cold starts and lots of highway miles running at operating temperature and low engine revolutions per mile, is likely less degraded than the 3k/6 month oil.

 

[crinkles]

i feel time is only much of a problem in cold climates, otherwise i just go by mileage within reason of course.

 

[mjoekingz28]

Mileage does not take into account idling.

 

[Gary Allan]

Originally Posted By: mjoekingz28
Mileage does not take into account idling.


Nor where the operation accumulates few miles over the run time of the engine.

Whichever is dominant is what you go with. Lots of time over few miles - time. Lots of miles over a short time - miles.

There are exceptions. The assumption usually includes somewhat frequent or daily use. If you, however, had an engine that operated in a higher mileage service, with long gaps between usage, then it skews that view a bit. Someone driving 50 miles every Sunday and leaving the thing sit the rest of the week should be able to go a long time without changing oil. Doing 2500/year with daily driving will be a different story.

 

[Liquid22]

Thanks for the insight guys!

In terms of acid formation, when does it really become a problem? Acids forming in oil is going to happen, hence the need for alkalinity (TBN), but at what point do they actually start to corrode engine internals?

 

[XS650]

Originally Posted By: LiquidZ
All,

Regarding oil change intervals, dealers/manufacturers will tell you to change your oil based on mileage OR time. As an example, 7000 miles OR 1 year is when you should change your oil.

My intuition leads me to believe that the mileage on an oil really determines when you should change it.



I believe they usually say words to the effect of 7000 miles or one year, whichever comes first. So, the two options aren't in conflict.

 

[Andyge]

I would say Mileage for me because I put on 20,000 a year on my car and 15,000 on my wife's car

Andy

 

[sangyup81]

Recommendations are made to allow for more highway miles and fewer city miles. That's why OEMs want you to change out Dino oil at 4 months in severe service even if you have fewer than 5,000 miles on them

 

[ahoier]

I never gave it much thought since I usually hit the miles mark, BEFORE the date mark

But yea....any vehicle that "sits" should be cranked over at least once a month just to get everything lubricated IMO....