This might be a dumb question to some but I am posting anyways. I have always changed the oil in my trucks every 3500 miles. I just realized that I have a oil life guage in my truck was wondering how accuate this was. Can you trust this? I use Mobil One oil in my trucks. Also does anyone know how this is "%" is calculated?

 

From what I have read it isn't just a time monitoring device. A lot of engineering went in to it and it is a pretty "smart" system. I am going 5000+ miles and using the Motorcraft synthetic blend oil.

 

Ford Engineers trust it, that's good enough for me.

 

its calculated on every 10,000 miles. atleast thats how it is for the 5.0. 1,000 miles=90% life, 2,000=80% life and so on.

 

It is quite good and a LOT of research went in to the model. I have an old document somewhere describing the GM oil life model (if I can find it I will share it). I'm sure Ford is just as good.

About the only thing that you should trust more is taking oil samples and sending in for analysis.

 

Intelligent Oil-Life Monitor™ Frequently Asked Questions

http://owner.ford.com/Storage/Common...IOLM%20FAQ.pdf

 

If it's half as good as the oil monitor system that was on my 06' GMC Sierra it's great. I won't know for quite awhile but I'm going to trust it, worst case I guess it will be time for a new truck again.

 

It takes driving parameters to give oil life percentages. It goes by how the truck is driven and how long it idles and how hard the engine works, etc. I tow a lot, and by 5000 miles, Im at about 6%, as opposed to 7500 mile normal driving oil change intervals. The computer senses that the engine works harder, so by 5k, I need to change my oil. I have good faith in the reading.

 

I must have deleted the document I had. Here's something I found concerning GM system so you can get an appreciation for how complex these things are. Any type of predictor is going to lean on the conservative side so don't worry about oil getting too worn. More details about an oil life monitoring system might be explained in SAE Paper 870403 (if you have access to those type of things).

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"The GM engine oil life monitor counts engine revolutions and accumulates the number for the basis of the oil life calculation. It then adds deterioration factors for operating temperature, start up temperature, soak times, ambient, coolant temperature, etc... There are a LOT of factors that "adjust" or affect the slope of the deterioration but the fundamental deterioration is traced back to the ZDP depletion that is inescapable with engine revolutions. The specific rate of ZDP depletion is readily measurable for any given engine so that is the fundamental item that is first calibrated for the oil life algorithm to tailor it specifically to that engine.

You would obviously like to get the oil out of the engine before the ZDP concentration gets so low that it is ineffective at being at the right place at the right time and preventing engine wear so that becomes the long term limit on oil life for that application.

The other things that determine oil life such a acid build up, oxidation, petane insuluables such as silicon from dust/dirt, carbon or soot build up from the EGR in blowby, water contamination, fuel contamination, etc.... are all modeled by the multipliers or deterioration factors that "adjust" the immediate slope of the line defined by the engine revolution counter as those items can be modeled in other ways and accounted for in the immediate slope of the ZDP depletion line.

The algorithm was developed over the course of many years by several lubrication experts at GM Fuels and Lubes, spearheaded by Doctor Shirley Schwartz who holds the patents (with GM) for the algorithm and the oil life montitor. I had the luck of working directly with Dr. Schwartz when the idea of the oil life monitor first progressed from the theoretical/lab stage to real world testing/development/validation. There were fleets of cars operated under all conditions that deteriorate the oil life for any and every reason and , thru oil sampling and detailed analysis of the oil condition, the algorithm was developed, fine tuned and validated to be the most accurate way invented yet to recommend an oil change interval by. As just one example, I have seen cars driven side-by-side on trips, one towing a trailer and one not, for instance, to prove the effectiveness of the oil life monitor in deteriorating the oil at a faster rate just because of the higher load, higher average RPM, higher temps, etc...and it works flawlessly.

The oil life monitor is so effective because: it is customized for that specific vehicle/engine, it takes everything into account that deteriorates the oil, it is ALWAYS working so as to take into account THAT INDIVIDUALS driving schedule, and it tailors the oil change to that schedule and predicts, on an ongoing basis, the oil life remaining so that that specific individual can plan an oil change accordingly. No other system can do this that effectively.

One thing is that I know personally from years of testing and thousands of oil analysis that the oil life algorithm works. There is simply no argument to the contrary. If you don't believe me, fine, but, trust me, it works. It is accurate because it has been calibrated for each specific engine it is installed on and there is considerable testing and validation of the oil life monitor on that specific application. ....the oil life monitor is very specific for that application.

Oil condition sensors in some BMW and Mercedes products are useful, also. They have their limitations, though, as they can be blind to some contaminates and can, themselves, be contaminated by certain markers or constituents of certain engine oils. Oil condition sensors can only react to the specific oil at that moment and they add complexity, cost and another potential item to fail. One other beauty of the GM oil life monitor is that it is all software and does not add any mechanical complexity, mass, wiring or potential failure mechanism.

There is considerable safety factor in the GM oil life monitor. Typically, I would say, there is a 2:1 safety factor in the slope of the ZDP depletion curve....in other words, zero percent oil life per the ZDP depletion is not zero ZDP but twice the concentration of ZDP considered critical for THAT engine to operate under all conditions reliably with no wear. This is always a subject of discussion as to just how low do you want the ZDP to get before the oil is "worn out" if this is the deciding factor for oil life. We would tend to be on the conservative side. If the oil life is counting down on a slope that would recommend a 10K change interval then there is probably 20K oil life before the ZDP is catostrophically depleted....not that you would want to go there...but reason why many people are successful in running those change intervals.

There are entire SAE papers written on the GM oil life monitor and one could write a book on it so it is hard to touch on all aspects of it in a single post. Hopefully we hit the high spots. Realize that a GREAT deal of time, work and energy went into developing the oil life monitor and it has received acclaim from engineering organizations, petroleum organizations, environmental groups all across the board. It is not some widget invented in a week and tacked onto the car."

 

It can't be calculated on every 10,000 miles. The odometer on my new 2012 F-150 is at 1,300 and oil is at 92%.

 

I think it does calcs based on when you last did a "reset". I think where 10K miles comes in to play is that it is the upper limit before the system will tell you to change oil no matter how much useful life is in the oil per the calculations.

 

I have never done a reset. And I think only the mechanic can do a reset on the oil life during maintenance.

 

It started keeping track the first time your truck was run at the factory.

Instructions to reset are always in the manual. You can do it if you want.

 

you can reset it your self! it is in the owners book

you can set the mileage set points to your liking.
if you wish to set it to 3500 you can.
you want 5000 you can set it there.
the only thing you cant set it above 10,000 miles or below 3000.
thats what my ford mechanic told me.
now the monitoring system can make changes. it needs to due to things like the way a motor is worked. he even told me it can sense the thickness and tell if oil is getting worn buy it's thickness witch i think was BS. but hey who now's with todays computers thinking and learning it just might do it.

 

Nope, you're instinct is correct - he's FOS.