Is the in car oil monitor accurate?

[Topic]

I just passed my oil maintenance due mileage, I'm now at about 5,003 miles and was supposed to change it at 4,986 but my oil life monitor in the car tells me i have 25% life left. How accurate is the oil monitor? I will still change it in the next few days but just wondering when it's the weekend and will probably put on another 20 miles before Monday servicing.

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[Neggytive]

it deducts life for age, my car went about 80 miles after changing the oil and got parked, that was a month ago and my oil life is already down to 91%

When I parked the car before that, in April the oil had 3100 miles on it and it was at 20%, by early August it was 4%, by the second week in August it was zero. The car never moved

I think their algorithm is crap.

so much for synthetics supposedly lasting longer

 

[LouG]

I just passed my oil maintenance due mileage, I'm now at about 5,003 miles and was supposed to change it at 4,986 but my oil life monitor in the car tells me i have 25% life left. How accurate is the oil monitor? I will still change it in the next few days but just wondering when it's the weekend and will probably put on another 20 miles before Monday servicing.

It's not that critical. It'll be fine.
During the mass supression of our population in 2021 my first service on that car was 4 months overdue. There was no concern from the dealer, and no one was doing high mileages anyway.

 

[Sofa King]

Probably accurate for their target mileage... though I think they use a higher target mileage (7,000?). Also based on time as well. If you change oil and reset the monitor then drive the 7,000 (or?) straight, you will get the prompt to change it. If you change it and reset, then park it for a year, it will also tell you to change it with 0 miles.

 

[JimC]

Unfortunately when Ford does an OTA update it resets the oil life monitor to 100% life (at least it always does on my car) for some reason. So anytime there is an update, the OLM is useless until your next oil change (that's why I have the windshield tag to keep an eye on the miles still).

 

[Neggytive]

I had an OTA done on 8/25, 2 weeks after the oil was changed, now 2 weeks later with the car not being started I am down to 91%

Ford's oil life calculations that drop it 8% month for age would not be right if mine was reset on 8/25

It would be right if I drove the car about 40 miles and let it sit for a month, 1% for the mileage driven and 8% for the supposed degradation of the oil from being exposed to atmosphere and the additives breaking down

 

[AZ_Ryan]

I had an OTA done on 8/25, 2 weeks after the oil was changed, now 2 weeks later with the car not being started I am down to 91%

Ford's oil life calculations that drop it 8% month for age would not be right if mine was reset on 8/25

It would be right if I drove the car about 40 miles and let it sit for a month, 1% for the mileage driven and 8% for the supposed degradation of the oil from being exposed to atmosphere and the additives breaking down

It is right. It goes off of time not just milage. If you change your oil and park the car for a year, it will go to zero. Because you should always replace once a year regardless of milage.

 

[AZ_Ryan]

This is an ongoing subject in many threads. And it's been pretty beat to death honestly.

The short answer is yes, it is accurate under most conditions. It calculates oil life based on time, milage, and diving conditions such as engine temps and RPMs.

That being said, It can't account for every variable such as dust, towing, and ambient temps. So while it is accurate, it should be used as a tool, not a substitute for common sense.

 

[robvas]

I think their algorithm is crap.

so much for synthetics supposedly lasting longer

the oil life monitor doesn't know what kind of oil you have in there

 

[Neggytive]

true, but Ford says full synthetic in the gen4 Coyote motors in the 7th gen Mustangs, so you'd figure their algorithm would be written for that.

 

[MAT1955]

The type of oil (semi or full synthetic) has nothing to do with the logarithm. It is time and mileage based. That said there have been some interesting arguments - particularly with third party warranty companies like Lubrico - when a customer doesn't put the mileage on but shows an oil change interval was passed.

 

[AZ_Ryan]

The type of oil (semi or full synthetic) has nothing to do with the logarithm. It is time and mileage based. That said there have been some interesting arguments - particularly with third party warranty companies like Lubrico - when a customer doesn't put the mileage on but shows an oil change interval was passed.

The algorithm is based on more than just time and mileage. It takes into account engine temperatures and RPMs. This has been demonstrated by anyone who has tracked their cars (including me). After a track day, the oil life is SIGNIFICANTLY lowered. Some OLMs have called for an oil change after just 2 days of hard driving.

 

[AZ_Ryan]

true, but Ford says full synthetic in the gen4 Coyote motors in the 7th gen Mustangs, so you'd figure their algorithm would be written for that.

It's doubtful the algorithm is programmed for a specific type of oil like synthetic blend or full synthetic. More than likely its a base average of oil viscosity the engineers came up with.

 

[MAT1955]

@A_Z .... yes I agree and I believe they use the "standard" oil their dealers provide which is Ford Semi Synthetic 5W-30. I know this because I got my first three oil changes "free" as part of a dealer purchase package but the oil is NOT full synthetic, because Ford considers semi synthetic 5W-30 perfectly fine, which may be but I do not - so I have to pay extra. Therefore, I would say semi synthetic oil specs are used and then mileage and time parameters are applied to set the "official" interval.

 

[gtstang462002]

It is right. It goes off of time not just milage. If you change your oil and park the car for a year, it will go to zero. Because you should always replace once a year regardless of milage.

I have been trusting the dash to tell me when to change the oil on all of my vehicles since I bought my 2011 Super duty. I change it when it tells me I have numerous vehicles bumping up on 200k miles doing this with no issues. My 2014 Fusion that I sold when I bought my Mustang had 190k on it with an average of 20k miles between oil changes(hybrid). 0 issues out of that car.

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