why OCI's are variable ?

[Brian123]

I'm hoping to get clarity on this. Assuming I am running a high end oil (HPL/Amsoil SS) and I don't have a turbo, please help me understand what exactly makes the oil lose its ability to protect the engine.

Is it:
1- fuel dilution
2- pH dropping
3- additives coming out of solution/consumed
4- VII loss
5- ?

Assume no oil loss, other consumption of the oil volume between changes. I watch several YT mechanics who consistently harp on 5k OCI regardless of driving styles, etc and I already pay for the high end oil/UOA/good filters. I am seeking clarity on what exactly causes the 5k OCI recommendation aside from historical precedent. TIA.

I will say this, a higher end oil like HPL or Amsoil SS will protect an engine better than a cheaper oil beyond 5000 miles. The YT mechanics harp on the 5K OCI because they are seeing engines that have probably been run on cheaper oils. The mechanics that are seeing these engines probably only had the oil changed based on the OLM or the oil was never checked during whatever OCI was going on.

Never assume no oil loss, this always happens to a certain extent, the higher end oils will have less consumption than the cheaper oils.

 

[earlyre]

thanks. How short is a "short trip"? If I'm driving at least 15 miles a trip, is that short still?

i'm the short trip posterboy.... I live 4.5 mi from work, AND drive a Hybrid... I stick to 5k mi synthetic oil changes. in my previous traditional ICE cars, i went 5k mi/ 6 mo, whichever came first. with this Hybrid, which calls for 10K mi OCI's, I go every 5K mi.

 

[CarlB]

I'm hoping to get clarity on this. Assuming I am running a high end oil (HPL/Amsoil SS) and I don't have a turbo, please help me understand what exactly makes the oil lose its ability to protect the engine.

Is it:
1- fuel dilution
2- pH dropping
3- additives coming out of solution/consumed
4- VII loss
5- ?

Assume no oil loss, other consumption of the oil volume between changes. I watch several YT mechanics who consistently harp on 5k OCI regardless of driving styles, etc and I already pay for the high end oil/UOA/good filters. I am seeking clarity on what exactly causes the 5k OCI recommendation aside from historical precedent. TIA.

UOA could help you see which "ability" the oil is losing in your application, then adjust OCI accordingly.

 

[Just a civilian pilot]

I can speak for the Honda oil life monitor that it’s definitely not just a countdown. It will call for shorter intervals with people who drive the cars harder and do more short trips.

Correct.

I have three Honda’s with OLM and log every oil change ( when it went to 0% ) and it can vary as much as 40% depending on how the car is driven and the operating environment.

It’s not “ counting”, it’s monitoring.

The highest I have seen it go to 0% on the Honda Civic was 12,062 miles to be exact.

 

[ecotourist]

Correct.

I have three Honda’s with OLM and log every oil change ( when it went to 0% ) and it can vary as much as 40% depending on how the car is driven and the operating environment.

It’s not “ counting”, it’s monitoring.

The highest I have seen it go to 0% on the Honda Civic was 12,062 miles to be exact.

I agree. I took my Accord on a long trip when the OLM was already high. With almost all highway driving on that trip, the OLM moved very little. The OLM never reached zero (I never let it reach zero) but the miles on that change were very high.

Clearly it's monitoring something more than miles, though I suspect miles are part of it.

I think my BMW monitored fuel consumption in its formula. City driving - fewer miles. Highway driving - more miles, but a similar amount of fuel.

 

[samven]

I dont think you can wear out the oil part of your motor oil in 5k or even 10k but add packs have a definite life and if they are working they are keeping dirt in solution. Your oil filter cannot filter 100% of the dirt and metal particularly the smaller sub 15 micron stuff and the oil just starts to turn into cutting fluid. I dont change my oil because its not slippery anymore I change it to get the dirt out and that can vary depending on your location, driving style and your engine.
I think the 5k OCI and OLM are just to make it easy to remember to change the oil.

 

[Kira]

Ha...Don't forget system capacity!
And surely oil temperature can effect OCI.
What are the engine longevity differences with vehicles fitted with oil coolers?

What are OCIs of haulers with 100 qt. systems?

 

[TomYoung]

Oil gets dirty over time, whether it is through ingestion in air, combustion products, incorrectly operating crankcase ventilation, it doesn’t really matter. Oil gets thick (with contaminants)and contaminated. Oil oxidizes and sometimes acidity/alkalinity changes. Over time, TBN depletes. There is every possibility that you oil might also take on water, and/or fuel. Your oil will only hold so much before it stops protecting your engine.

Whether or not you choose a high end oil or not, the dirtiness of the oil increases, TBN and additive packs deplete. The idea that there should be an exemption because of choosing an expensive oil perhaps speaks to your expectation of justice in the universe.

My take is that the folks who use mainstream oils and filters in their regular cars every 5,000 miles or so, do much better in avoiding oil related failure in the long run.

I would point out that you are free to use high end oil with shorter oil changes…

 

[Kira]

^^...been saying this for years...Get the dirt out.

SARCASM:
Do an oil analysis or two and use a bias eye to protract an OCI which mimics at least one found on the orthodox list. 3K, 5K 7.5K for owners of grocery getters. These folk have merely to change their oil on time to rid themselves of dirt.

Enter the realm of multiples of 5 over 10K; 10K, 15K and 20K for oil and filters. You know what you're talking about.
Even though extremely high performance oils are used, you can still run 'em dirty.

Better to change early.

 

[SC Maintenance]

Additional items - I don't think were mentioned.

-- Depends on how much oil is actually in the sump. More oil = takes longer to heat up. Also lasts longer likely.
-- Depends on engine design - ie long chains shear oil, belts generally do not - for example.

 

[Leroybrown]

It's a combination of factors depending on the engine and the use case.

 

[ripcord]

---

If keeping it simple and safe is the goal, just changing every April and every October with whatever decent quality synthetic is on sale will be highly likely to keep the motor working fine until something else kills the car.

 

[gasman556]

Oil gets dirty over time, whether it is through ingestion in air, combustion products, incorrectly operating crankcase ventilation, it doesn’t really matter. Oil gets thick (with contaminants)and contaminated. Oil oxidizes and sometimes acidity/alkalinity changes. Over time, TBN depletes. There is every possibility that you oil might also take on water, and/or fuel. Your oil will only hold so much before it stops protecting your engine.

Whether or not you choose a high end oil or not, the dirtiness of the oil increases, TBN and additive packs deplete. The idea that there should be an exemption because of choosing an expensive oil perhaps speaks to your expectation of justice in the universe.

My take is that the folks who use mainstream oils and filters in their regular cars every 5,000 miles or so, do much better in avoiding oil related failure in the long run.

I would point out that you are free to use high end oil with shorter oil changes…

Good info. Odd philosophical assumption. Thanks anyways.

Additional items - I don't think were mentioned.

-- Depends on how much oil is actually in the sump. More oil = takes longer to heat up. Also lasts longer likely.
-- Depends on engine design - ie long chains shear oil, belts generally do not - for example.

“Solution to pollution” type scenario for increased sump volume I’m thinking. Thanks for this. Makes sense.

^^...been saying this for years...Get the dirt out.

SARCASM:
Do an oil analysis or two and use a bias eye to protract an OCI which mimics at least one found on the orthodox list. 3K, 5K 7.5K for owners of grocery getters. These folk have merely to change their oil on time to rid themselves of dirt.

Enter the realm of multiples of 5 over 10K; 10K, 15K and 20K for oil and filters. You know what you're talking about.
Even though extremely high performance oils are used, you can still run 'em dirty.

Better to change early.

This is my frustration in modern filters becoming so shoddily constructed. We live in the best time in recorded history to exist, yet we keep churning out trash tier filtration to go along with world class oils. Frustrating indeed.

 

[Hohn]

I'm hoping to get clarity on this. Assuming I am running a high end oil (HPL/Amsoil SS) and I don't have a turbo, please help me understand what exactly makes the oil lose its ability to protect the engine.

Is it:
1- fuel dilution
2- pH dropping
3- additives coming out of solution/consumed
4- VII loss
5- ?

Assume no oil loss, other consumption of the oil volume between changes. I watch several YT mechanics who consistently harp on 5k OCI regardless of driving styles, etc and I already pay for the high end oil/UOA/good filters. I am seeking clarity on what exactly causes the 5k OCI recommendation aside from historical precedent. TIA.

It's all those and more.

The YT mechanics preaching 5k are no different than the old mechanics 30 years ago pushing 3k. One size doesn't fit all, just because it's big enough to fit over them.

Pistons do not seal perfectly and fuels do not burn fully. So the oil ends up with combustion byproducts in it.

Hot contamination of oil causes degradation in many forms. The majority of oil degradation is chemical.


But there's also a physic degradation of the oil relating the oil shear as well. It's just a lot less severe.

Oil degrades at a rate that highly correlates to the amount of fuel the engine has consumed. So the amount of fuel burned is what defines the oil life.


Hence the best rule of thumb for oil change intervals that I know of: change the oil when you've consumed that amount of fuel that is 200x the oil pan capacity. This gem of a tip was given to me by a former colleague who ran the oil labs at SWRI. If you run the math, it's surprisingly applicable universally for most street-driving duty cycles. It correctly shortens your OCI for cold engines/stop/start driving vs highway driving.

For example, if my wife is driving my GX460 with her usage and lead foot, it's getting 13mpg and I'd have a calculated OCI of 5200 miles, but with my usage (much more highway), it get 18mpg, so the OCI for me would be 7200 miles. I change it at 5k just for convenience.

 

[Hohn]

This is my frustration in modern filters becoming so shoddily constructed. We live in the best time in recorded history to exist, yet we keep churning out trash tier filtration to go along with world class oils. Frustrating indeed.

This is not universally true. What *is* universally true is that the market will provide what people are willing to pay for. I hope that the same group of people lamenting poor filter quality aren't the same ones complaining that filters cost $8 instead of $5.

Of course, the converse also exists-- nobody makes a $20 filter worth the $20 because nobody will pay $20 for a truly premium filter.

 

[SC Maintenance]

This is my frustration in modern filters becoming so shoddily constructed.

Oil filters have always been an illusion, because even the best ones capture 99% of 20um and maybe 50% of 10 um. There are plenty of studies in industrial machines showing particles down to 1um causing lots of mechanical wear - which no filter would ever capture - except maybe a bypass filter.

So while I agree with your assessment of shoddy current filter selection, its not really changed anything - they never did catch the small stuff. If you want all the small particles gone you need to shorten the OCI. I am told Bob - the founder of this site, didn't even believe in oil filters.

 

[Samurai1225]

Disagree about OLM's (Honda/Toyota anyways) as all they are is another trip computer you reset IME. Zero input via driving trip length/idle time/etc vs just a simple 10k trip countdown. GM's supposedly is dialed in - the Honda/Toyota's not so much.


Italian tune up maybe?

Good filtration is a solid point, sure! Assume this is taken into consideration.

This is absolutely NOT true at least when it comes to Honda's OLM. It is not simply a mileage countdown. I know this from owning many Hondas in the past as well as literature on Honda's OLM citing the parameters / metrics it uses in determining remaining oil life.

 

[gasman556]

Oil filters have always been an illusion, because even the best ones capture 99% of 20um and maybe 50% of 10 um. There are plenty of studies in industrial machines showing particles down to 1um causing lots of mechanical wear - which no filter would ever capture - except maybe a bypass filter.

So while I agree with your assessment of shoddy current filter selection, its not really changed anything - they never did catch the small stuff. If you want all the small particles gone you need to shorten the OCI. I am told Bob - the founder of this site, didn't even believe in oil filters.

Woah, not believing in filters?!?!? Old school indeed!!!

I guess this makes the case for bypass filter setups. One guy with a 800k Cummins had a custom setup he made and the YT guy (Dave’s auto center) breaking it down showing almost no bearing or cam wear. It was impressive! Too bad there’s not an off the shelf solution for this.

This is not universally true. What *is* universally true is that the market will provide what people are willing to pay for. I hope that the same group of people lamenting poor filter quality aren't the same ones complaining that filters cost $8 instead of $5.

Of course, the converse also exists-- nobody makes a $20 filter worth the $20 because nobody will pay $20 for a truly premium filter.

I’ve got to be frank, if a filter cost $20 and the value was there I would buy it. I know I’m in the minority, but I’m serious. My amsoil emails speak to this.

 

[gasman556]

This is absolutely NOT true at least when it comes to Honda's OLM. It is not simply a mileage countdown. I know this from owning many Hondas in the past as well as literature on Honda's OLM citing the parameters / metrics it uses in determining remaining oil life.

Cool. Agree to disagree. Still zero variance for me and mine on the 10k oci “minder.”

 

[Hohn]

Oil filters have always been an illusion, because even the best ones capture 99% of 20um and maybe 50% of 10 um. There are plenty of studies in industrial machines showing particles down to 1um causing lots of mechanical wear - which no filter would ever capture - except maybe a bypass filter.

So while I agree with your assessment of shoddy current filter selection, its not really changed anything - they never did catch the small stuff. If you want all the small particles gone you need to shorten the OCI. I am told Bob - the founder of this site, didn't even believe in oil filters.

"lots" of mechanical wear?

That's a pretty imprecise term. And yet I'm seeing QSK60s hit 1.3 million gallon burn before overhaul with just an Alfa Laval Eliminator not known for superb filtering efficiency (it's worse than a 30 micron absolute spin-on) and dino Shell Rimula on 1000hr or longer drains.

Whatever amount of wear is occurring due to "poor" filtration, it's not big enough to limit the life of the product enough to where the mine operators are willing to run superior spin-ons.