why OCI's are variable ?

[OVERKILL]

Motor oil deteriorates with TIME, although the rate seems slower while it is inside a sealed container.

RUNNING TIME (hours) is a popular factor for industrial equipment.

CALENDAR TIME is more "extreme". In general aviation, some engines require annual oil changes, even with zero hours. Those are extreme conditions with leaded fuel. Our GM cars have a OCI alert that seems to have 1 year as a factor (GM highlighted some other factors in factor documentation like mileage, driving habits, etc but I can't remember them).

The impact of time, relative to the other factors I've listed, is low on the significance scale. Time is included as a factor by OEM's (usually a blanket one year) due to factors outside of the OLM's algorithm, such as condensation/moisture, and the impact of acids and other combustion byproducts sitting in a static product as contaminants which may work to degrade it.

Engine hours (running time) is a much better base metric than miles, as is fuel consumed (litres or gallons).

 

[OVERKILL]

Maybe cite a more relevant example next time. A vehicle with Mobil1 as factory fill suggests that operating cost isn't the #1 factor for that vehicle.

Your example doesn't rebut my point. It's a red herring.

Find a Toyota or Kia that did the same thing on factory 5w20 or jiffy lube commodity oil and you'll have a good rebuttal point.

Toyota doesn't have an iOLM though, it's just a mileage counter, so it runs contrary to the OLM's we are discussing here, as it takes absolutely no part of the operating profile into consideration.

 

[UncleDave]

The impact of time, relative to the other factors I've listed, is low on the significance scale. Time is included as a factor by OEM's (usually a blanket one year) due to factors outside of the OLM's algorithm, such as condensation/moisture, and the impact of acids and other combustion byproducts sitting in a static product as contaminants which may work to degrade it.

Engine hours (running time) is a much better base metric than miles, as is fuel consumed (litres or gallons).

I wish all my stuff had an hour meter.

 

[OVERKILL]

I wish all my stuff had an hour meter.

Yeah, I've started recording engine hours when I change the oil on the wife's truck due to a conversation @The Critic and I had about it, which piqued my interest in how it influenced the OLM.

 

[Patman]

Maybe cite a more relevant example next time. A vehicle with Mobil1 as factory fill suggests that operating cost isn't the #1 factor for that vehicle.

Your example doesn't rebut my point. It's a red herring.

Find a Toyota or Kia that did the same thing on factory 5w20 or jiffy lube commodity oil and you'll have a good rebuttal point.

There are plenty of rebuttals out there. Just look up a few responses in this very thread actually, post #50. Just because you think you are smarter than the engineers who designed these OLMs doesn’t make it true

 

[Patman]

Toyota doesn't have an iOLM though, it's just a mileage counter, so it runs contrary to the OLM's we are discussing here, as it takes absolutely no part of the operating profile into consideration.

Bingo!

 

[WobblyElvis]

If you don't have an OLM, fuel consumption can be used to help determine an OCI.

 

[Hohn]

Curious, partially growing up in Northern Indiana.

Where is diesel central?

Columbus, home of the mighty Cummins diesel.

 

[dpalmer1987]

Generally, these YT mechanics are just that; they are not tribologists. Many of them make assumptions based on poor information, and lack of understanding. Further, it's easy for them to offer a one-size-fits-all answer; makes for less discussion and nuance of explanation.

The reality is that any lubricant can be over or under utilized. So, for any given application and use, some lubes will be more capable than others, depending on a host of factors well discussed on this site dozens thousands of times ...

What you overlook is that there are additional considerations, not just any expected/actual oil change interval. What if I want my car to be looked at (preventative maintenance multipoint inspections etc., especially while on a lift) every 5k miles and while doing so just go ahead and get my oil changed (and tires rotated etc.). To simply come in (every 5k?) for periodic inspection (and tire rotation etc.) but not change the oil is not (to me) the optimal utilization of one's limited time to be devoted to vehicle maintenance.

If you want to say just come in every 10k (for example) for this purpose - don't you yourself say there is no one-size-fits-all answer? I hope you are not saying that one should actually solely schedule maintenance time-intervals based on the variability (which would itself vary over time due to various other factors) of some supposed truly(?) comprehensive oil analysis? Are there not additional mechanical sub/components that will/would call for different maintenance time-intervals than what would be called for solely by engine oil analysis? So you think it is reasonable (for example) to come in for tire rotation every 5k miles (as Toyota advocates) and also come in for oil changes every 7.5k miles? Not very many people would do such a thing.

The point is that any supposed optimal oil utilization interval is not necessarily the most significant consideration in scheduling vehicle maintenance intervals. People (such as the so-called "YT mechanics") come/came up with so-called "rules of thumb" for a reason - they actually serve a purpose. So why not decline (if that is your choice) the many motor oil products optimized for long(er) oil drain intervals (and the inherent compromises necessary for such product qualities) in favor of oils that only allow for shorter (5k?) intervals (thus allowing for other product feature optimization made possible by being able to avoid the compromises required for the longer oil drain interval feature)?

 

[doublebase]

I think “rules of thumb” oil change intervals are so popular because no one really knows exactly when to change their oil on any given run. Too many variables. It’s like trying to time the stock market, you’re going to miss the dip. And you settle on a rule of thumb, like you settle on dollar cost averaging monthly. And I think that’s fine. YT techs say 5,000 miles because of those variables and because they’re looking for a one size fits all answer, because that’s what most want. One size fits all, easy.

If you really want to guesstimate your oil change interval, personally I research the engine - I want to know if it’s a fuel diluter and oil consumer - and I want to know if there are any known inherent problems with the engine BEFORE making a guesstimate of an interval based off driving tendencies and daily commute. Then I make a decision and check my oil level frequently. My current engine is able to handle longer intervals, I’ve determined this by everything I’ve just written ^^^ and a few oil analysis’s. Which show almost identical results no matter if I’m running Amsoil Signature Series or Mobil1 (both of which were identically very good). And I’ve settled on a nice round number I’m comfortable with, I’m sure it’s not 100% perfectly accurate but like I said, I don’t think anyone knows consistently what that is.

 

[OVERKILL]

I think “rules of thumb” oil change intervals are so popular because no one really knows exactly when to change their oil on any given run. Too many variables. It’s like trying to time the stock market, you’re going to miss the dip. And you settle on a rule of thumb, like you settle on dollar cost averaging monthly. And I think that’s fine. YT techs say 5,000 miles because of those variables and because they’re looking for a one size fits all answer, because that’s what most want. One size fits all, easy.

If you really want to guesstimate your oil change interval, personally I research the engine - I want to know if it’s a fuel diluter and oil consumer - and I want to know if there are any known inherent problems with the engine BEFORE making a guesstimate of an interval based off driving tendencies and daily commute. Then I make a decision and check my oil level frequently. My current engine is able to handle longer intervals, I’ve determined this by everything I’ve just written ^^^ and a few oil analysis’s. Which show almost identical results no matter if I’m running Amsoil Signature Series or Mobil1 (both of which were identically very good). And I’ve settled on a nice round number I’m comfortable with, I’m sure it’s not 100% perfectly accurate but like I said, I don’t think anyone knows consistently what that is.

But that's the entire point of iOLM's, they take operating conditions into account to determine the OCI length. Going by some arbitrary static mileage figure doesn't.

 

[doublebase]

But that's the entire point of iOLM's, they take operating conditions into account to determine the OCI length. Going by some arbitrary static mileage figure doesn't.

Does it take its own engine’s flaws into account? I don’t know of many manufacturers willing to admit they built a fuel diluter, instead years later they may adjust the oil life distance down. Do they take oil consumption into account? Oil level in the engine? These scenarios are different than just pure operating conditions. Will manufactures take into account that they designed an engine that dilutes oil with fuel while also building an engine with an inherent design flaw that causes the engine to consume oil (like piston rings or piston design for example). And then put those considerations into iOLM’s?

If so, sure, all static mileage figures can be eliminated.

 

[OVERKILL]

Does it take its own engine’s flaws into account? I don’t know of many manufacturers willing to admit they built a fuel diluter, instead years later they may adjust the oil life distance down. Do they take oil consumption into account? Oil level in the engine? These scenarios are different than just pure operating conditions. Will manufactures take into account that they designed an engine that dilutes oil with fuel while also building an engine with an inherent design flaw that causes the engine to consume oil (like piston rings or piston design for example). And then put those considerations into iOLM’s?

If so, sure, all static mileage figures can be eliminated.

I do think that the OEM's do try and take the engine's characteristics into account. Many DI engines fuel dilute, how they weigh that in the algorithm is of course proprietary. I assume engines with electronic oil level sensors may take oil level into account. They also take sump volume into account.

Toyota of course doesn't use an iOLM as I mentioned earlier, it's a dumb mileage counter. Not sure about KIA or other engines with a reputation for oil consumption, but the Theta's had a lot more wrong with them than how frequently you changed the oil.

Last OCI on my wife's truck (which was extended), we put 710 hours on the oil and 22,124km (13,747 miles) with the HPL "overkill" 0W-20. This is an engine that doesn't fuel dilute and isn't DI and has a 7 quart sump, but it spec's a generic 5W-20 and so the iOLM intervals range from ~10,000 to ~14,000km (6,200 to 8,700 miles) depending on operating conditions.

This most recent interval, that's an average speed of 31km/h (19.36Mph). That's not very fast. Had we been driving to the cottage a lot, that number of engine hours would have been greatly reduced and subsequently the average speed considerably higher. Fuel consumption would have also been lower. These are factors (hours, fuel burned) that have a significant impact on the health of the lubricant, as was discussed earlier in the thread, but are not in any way factored-in to the "miles" based change interval (and of course Toyota's mileage counter). This is why some engines running dealer bulk at some mileage interval are pristine while others, using the same oil, changed at the same interval, are varnish city.

Mileage is a poor proxy for oil condition, just like trying to use "miles" to measure EV charge speed. Both are used because they are easy and don't require much thought (or learning new units in the case of the latter) and OEM's are aware of this, which is why we saw iOLM's enter the picture. It's also why much more expensive equipment has service intervals based on hours and/or volume of fuel used, both of which are considerably better proxies for oil condition.

If you are uncomfortable with the idea of following the iOLM, you'd be better served using engine hours or fuel burned.

 

[ripcord]

I like changing oil. 5k changes are safe and effective.

 

[Bullwinkle007]

Ahh. All this OLM business. MY DI 3.5L. Gets changed every 3k M1 ESP 0/30. Purchased used 99k clock

2024 Ram 1500. 3.6L M1 0/40 multi port. 3k OCI. Purchased brand new. First OCI 100 miles did every 500 miles until it reached 5K miles. Will keep until it’s dead

 

[doublebase]

I do think that the OEM's do try and take the engine's characteristics into account. Many DI engines fuel dilute, how they weigh that in the algorithm is of course proprietary. I assume engines with electronic oil level sensors may take oil level into account. They also take sump volume into account.

Toyota of course doesn't use an iOLM as I mentioned earlier, it's a dumb mileage counter. Not sure about KIA or other engines with a reputation for oil consumption, but the Theta's had a lot more wrong with them than how frequently you changed the oil.

Last OCI on my wife's truck (which was extended), we put 710 hours on the oil and 22,124km (13,747 miles) with the HPL "overkill" 0W-20. This is an engine that doesn't fuel dilute and isn't DI and has a 7 quart sump, but it spec's a generic 5W-20 and so the iOLM intervals range from ~10,000 to ~14,000km (6,200 to 8,700 miles) depending on operating conditions.

This most recent interval, that's an average speed of 31km/h (19.36Mph). That's not very fast. Had we been driving to the cottage a lot, that number of engine hours would have been greatly reduced and subsequently the average speed considerably higher. Fuel consumption would have also been lower. These are factors (hours, fuel burned) that have a significant impact on the health of the lubricant, as was discussed earlier in the thread, but are not in any way factored-in to the "miles" based change interval (and of course Toyota's mileage counter). This is why some engines running dealer bulk at some mileage interval are pristine while others, using the same oil, changed at the same interval, are varnish city.

Mileage is a poor proxy for oil condition, just like trying to use "miles" to measure EV charge speed. Both are used because they are easy and don't require much thought (or learning new units in the case of the latter) and OEM's are aware of this, which is why we saw iOLM's enter the picture. It's also why much more expensive equipment has service intervals based on hours and/or volume of fuel used, both of which are considerably better proxies for oil condition.

If you are uncomfortable with the idea of following the iOLM, you'd be better served using engine hours or fuel burned.

I don’t currently own a vehicle with an iOLM, I own a Toyota. I developed my own algorithm for it, basically researched the engine (naturally aspirated port injected V6), not known to be an oil user, easy highway commute and a few UOA’s using a different oils.

I would trust an iOLM if I was confident enough in it. My last one…let’s just say I wasn’t all that confident. 2018 Silverado. Direct injection, dipstick smelt like fuel half the time, oil consumption from day one, misfire codes. OLM would tell me everything was ticking along A OK and then rapidly drop to 0% when I hit the 7,500 mile mark. Didn’t care if I was a quart low or half the crankcase was filled with gasoline. Traded it in at 50,000 miles. Babied and highway driven since day one off the lot. So, yeah I’d have to research and form a trust in the monitor to strictly go by that. And sounds like you have a good one in your (Dodge Ram I’m assuming?).

 

[OVERKILL]

I don’t currently own a vehicle with an iOLM, I own a Toyota. I developed my own algorithm for it, basically researched the engine (naturally aspirated port injected V6), not known to be an oil user, easy highway commute and a few UOA’s using a different oils.

I would trust an iOLM if I was confident enough in it. My last one…let’s just say I wasn’t all that confident. 2018 Silverado. Direct injection, dipstick smelt like fuel half the time, oil consumption from day one, misfire codes. OLM would tell me everything was ticking along A OK and then rapidly drop to 0% when I hit the 7,500 mile mark. Didn’t care if I was a quart low or half the crankcase was filled with gasoline. Traded it in at 50,000 miles. Babied and highway driven since day one off the lot. So, yeah I’d have to research and form a trust in the monitor to strictly go by that. And sounds like you have a good one in your (Dodge Ram I’m assuming?).

Yeah, the FCA/Stellantis one seems to be pretty good.

Does your Toyota provide you with engine hours? I suppose you could track fuel consumption manually, but I appreciate that it's a lot of work.

 

[Nessism1]

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.

I have not experienced that with my Civic.

 

[Bullwinkle007]

Not going to lead to much of a "discussion" if you just refuse to acknowledge facts and nuance. This isn't really something you can "agree to disagree" on, either you acknowledge that the Honda OLM being discussed with those you are discussing it is not simply a mileage counter as you've claimed and they've evidenced, or you willfully refuse to accept that relevant information, in which case there's really no reason to continue conversing.

My experience with my 2015 Acura. The OLM does more than mileage. In the winter time, she sees a lot of idle time from the cold, and when I get off work, I don’t want to get in a cold car after working in the cold. She will idle 30 min before and after work. Helps with getting the snow off the car and getting the glass warm. Anyways, at 500 miles on the OCI from idle time, she will drop 10% on the OLM. That car sees 3k OCI anyways. I don’t reset the trip meter because I wanna know what the maintenance codes are when it hits 15%.