How does olm work and how accurate
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Originally Posted By: Vikas
Has somebody ever sent out the same sample twice for UOA and has got identical results?
One example:
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3248519/One_Oil_-_Two_Labs_-_Two_Diffe
Has somebody ever sent out the same sample twice for UOA and has got identical results?
One example:
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3248519/One_Oil_-_Two_Labs_-_Two_Diffe
Originally Posted By: CELICA_XX
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I agree. That seems to be my finding with my Impala. 92 miles per percentage point, regardless of the type of driving, ambient temp, way I drive, etc.
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I agree. That seems to be my finding with my Impala. 92 miles per percentage point, regardless of the type of driving, ambient temp, way I drive, etc.
I have been changing oil in my '03 Alero, with the 3400 V6, to the OLM interval for over 183,000 miles now. And judging from what I can see through the oil fill, the engine interior looks great. I'd go snap a picture and attach, but I have never attached pictures here and don't know how. (Guess I need to learn). Being somewhat new here, I have yet to send in a uoa off this car.
My OLM typically goes off between 6,500 and 6,800 miles. I have been told by others that the GM OLM system is more complex. But according to the Owner's Manual, the OLM in my Alero uses engine revolutions and engine temperature as the inputs to calculate oil life.
My OLM typically goes off between 6,500 and 6,800 miles. I have been told by others that the GM OLM system is more complex. But according to the Owner's Manual, the OLM in my Alero uses engine revolutions and engine temperature as the inputs to calculate oil life.
Originally Posted By: CELICA_XX
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
Patman
Staff member
The OLM in my Corvette (and the 98 Corvette I had previously) definitely works well, as I drive my Corvettes pretty gently compared to other friends of mine (many of which track their cars) and I get significantly longer mileage before mine count down to zero. I'm at 3000 miles on my current fill and it's still showing 75% oil life, while I know others who are already at 50% or lower at this point.
Originally Posted By: Benzadmiral
Originally Posted By: CELICA_XX
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
Originally Posted By: CELICA_XX
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
Since we only own GM products in a service fleet we have limited experience.
But it has been pretty good IMO. Just sold an 04 van with half a million very hard miles. The engine was silent, smooth, and neither leaked nor burned oil.
Used whatever synthetic was on sale, same with filters, and changed only via OLM.
Note that we have had Silverados go almost 14k miles before lighting up the alert, yet our vans go no more than 4500 miles or so, as they do tons of stationary operation at 1500-1750 rpm...
But it has been pretty good IMO. Just sold an 04 van with half a million very hard miles. The engine was silent, smooth, and neither leaked nor burned oil.
Used whatever synthetic was on sale, same with filters, and changed only via OLM.
Note that we have had Silverados go almost 14k miles before lighting up the alert, yet our vans go no more than 4500 miles or so, as they do tons of stationary operation at 1500-1750 rpm...
Originally Posted By: cp3
Originally Posted By: Benzadmiral
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
It might be affected by temps a little, but the OLM didn't seem to drop much faster in the cold temps I saw in January and February than it does now. The Regal's OLM seems to drop about 15% a month, and I drive about 900-1000 miles a month, 70% city. So in 4 months I use about 60% of the oil's life. It was pretty much the same for my first oil change period, with cooler weather, as it was for the last one, with hot temps every day.
Originally Posted By: Benzadmiral
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
It might be affected by temps a little, but the OLM didn't seem to drop much faster in the cold temps I saw in January and February than it does now. The Regal's OLM seems to drop about 15% a month, and I drive about 900-1000 miles a month, 70% city. So in 4 months I use about 60% of the oil's life. It was pretty much the same for my first oil change period, with cooler weather, as it was for the last one, with hot temps every day.
Originally Posted By: Benzadmiral
Originally Posted By: cp3
Originally Posted By: Benzadmiral
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
It might be affected by temps a little, but the OLM didn't seem to drop much faster in the cold temps I saw in January and February than it does now. The Regal's OLM seems to drop about 15% a month, and I drive about 900-1000 miles a month, 70% city. So in 4 months I use about 60% of the oil's life. It was pretty much the same for my first oil change period, with cooler weather, as it was for the last one, with hot temps every day.
IMO outside temp is a minor detail to affect oil life. It is the oil temp that determines if it was a short trip or not. My guess is it counts RPM's at hot oil temp and RPM's at low oil temp differently. RPM's at hot oil temp being easier on the oil compared to low oil temp. Short trip, city driving etc are not quantitative to calculate oil life.
Originally Posted By: cp3
Originally Posted By: Benzadmiral
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
It might be affected by temps a little, but the OLM didn't seem to drop much faster in the cold temps I saw in January and February than it does now. The Regal's OLM seems to drop about 15% a month, and I drive about 900-1000 miles a month, 70% city. So in 4 months I use about 60% of the oil's life. It was pretty much the same for my first oil change period, with cooler weather, as it was for the last one, with hot temps every day.
IMO outside temp is a minor detail to affect oil life. It is the oil temp that determines if it was a short trip or not. My guess is it counts RPM's at hot oil temp and RPM's at low oil temp differently. RPM's at hot oil temp being easier on the oil compared to low oil temp. Short trip, city driving etc are not quantitative to calculate oil life.
Make some assumptions based upon miles driven per start, ambient temperatures, revs and fuel used and throw a little math at those figures and you have an IOLM.
How accurate it is will depend upon how accurate the assumptions were of their effects on oil life.
A well validated system is a pretty accurate way of determining a conservative but not ridiculously short drain interval.
How accurate it is will depend upon how accurate the assumptions were of their effects on oil life.
A well validated system is a pretty accurate way of determining a conservative but not ridiculously short drain interval.
Originally Posted By: RhondaHonda
Originally Posted By: CELICA_XX
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I agree. That seems to be my finding with my Impala. 92 miles per percentage point, regardless of the type of driving, ambient temp, way I drive, etc.
The Regal, which has the same engine as Celica's Equinox, also drops a point every 60 miles or so. I have 310 miles on the current fill. The OLM is reporting 95% life left.
Originally Posted By: CELICA_XX
I have no experience with the Ford OLM, but I have absolutely no faith in the GM "algorithm"
I service a 2.4 Ecotec that always sees severe service. Many short trips and long hours of idling per day. It averages 62 miles per percentage point.
Last month I changed the oil/filter, reset the computer back to 100%, and took off for a road trip out of state.
Upon returning home with all gentle highway miles, it still counts at 62 miles per 1 percent drop.
I agree. That seems to be my finding with my Impala. 92 miles per percentage point, regardless of the type of driving, ambient temp, way I drive, etc.
The Regal, which has the same engine as Celica's Equinox, also drops a point every 60 miles or so. I have 310 miles on the current fill. The OLM is reporting 95% life left.
Originally Posted By: Nate1979
Originally Posted By: Benzadmiral
Originally Posted By: cp3
Originally Posted By: Benzadmiral
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
It might be affected by temps a little, but the OLM didn't seem to drop much faster in the cold temps I saw in January and February than it does now. The Regal's OLM seems to drop about 15% a month, and I drive about 900-1000 miles a month, 70% city. So in 4 months I use about 60% of the oil's life. It was pretty much the same for my first oil change period, with cooler weather, as it was for the last one, with hot temps every day.
IMO outside temp is a minor detail to affect oil life. It is the oil temp that determines if it was a short trip or not. My guess is it counts RPM's at hot oil temp and RPM's at low oil temp differently. RPM's at hot oil temp being easier on the oil compared to low oil temp. Short trip, city driving etc are not quantitative to calculate oil life.
But what are you guys considering as cold outside temps? We have at least a few days here most winters where morning start temps are -30C. Summer morning starts can occasionally be pushing +30C, not this year however and would typically be high teens low-mid twenties. My understanding of the GM OLM was that it took a substantial hit for cold starts.
Something has to account for a summer 10000km and a winter 5000km OCI by the OLM that I've seen in the G6. Those were similar usage but I've seen as low as 3000km last winter with nothing but short trips.
Originally Posted By: Benzadmiral
Originally Posted By: cp3
Originally Posted By: Benzadmiral
I saw the same thing with my trip to Amarillo in May. Two thousand miles, nearly all highway, and the OLM wound up about the same as if I'd driven the car on my regular 70% city routine for two months.
I wonder if GM's OLM is based heavily on temperatures. My experience is more like Patman's. The G6 varies drastically from summer to winter. The G5 did as well just not as much, I checked my spreadsheets and saw from 190km/% to 140km/%.
It might be affected by temps a little, but the OLM didn't seem to drop much faster in the cold temps I saw in January and February than it does now. The Regal's OLM seems to drop about 15% a month, and I drive about 900-1000 miles a month, 70% city. So in 4 months I use about 60% of the oil's life. It was pretty much the same for my first oil change period, with cooler weather, as it was for the last one, with hot temps every day.
IMO outside temp is a minor detail to affect oil life. It is the oil temp that determines if it was a short trip or not. My guess is it counts RPM's at hot oil temp and RPM's at low oil temp differently. RPM's at hot oil temp being easier on the oil compared to low oil temp. Short trip, city driving etc are not quantitative to calculate oil life.
But what are you guys considering as cold outside temps? We have at least a few days here most winters where morning start temps are -30C. Summer morning starts can occasionally be pushing +30C, not this year however and would typically be high teens low-mid twenties. My understanding of the GM OLM was that it took a substantial hit for cold starts.
Something has to account for a summer 10000km and a winter 5000km OCI by the OLM that I've seen in the G6. Those were similar usage but I've seen as low as 3000km last winter with nothing but short trips.
My winter is blink-and-you'll-miss-it, usually only January and February, and is not often cold. But it is a damp, penetrating cold, and the car does take a bit longer to get to operating temp than it does when temperatures are 77-80 F. at dawn, and 95 F. at 4 pm.
The GM OLM is widely regarded as one of the better ones.
There was a great thread here long ago where one of the engineers explained how it counted every single crank revolution, duration at temp, miles traveled, and much more.
I believe when you are talking temps it is far more concerned with engine temp than ambient temp, it is looking for the amount of time spent running cold...
There was a great thread here long ago where one of the engineers explained how it counted every single crank revolution, duration at temp, miles traveled, and much more.
I believe when you are talking temps it is far more concerned with engine temp than ambient temp, it is looking for the amount of time spent running cold...
I wonder if GM's OLM takes into account length of service? For example, cars that are stored for the winter.
Originally Posted By: SteveSRT8
The GM OLM is widely regarded as one of the better ones.
There was a great thread here long ago where one of the engineers explained how it counted every single crank revolution, duration at temp, miles traveled, and much more.
I believe when you are talking temps it is far more concerned with engine temp than ambient temp, it is looking for the amount of time spent running cold...
There is no way it counts engine revs...
This car will sometimes have to idle for 3 hours while parked and the OLM will remain constant.
The GM OLM is widely regarded as one of the better ones.
There was a great thread here long ago where one of the engineers explained how it counted every single crank revolution, duration at temp, miles traveled, and much more.
I believe when you are talking temps it is far more concerned with engine temp than ambient temp, it is looking for the amount of time spent running cold...
There is no way it counts engine revs...
This car will sometimes have to idle for 3 hours while parked and the OLM will remain constant.
Here is a previous thread on the GM OLM from an ex-GM engineer:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1735142
Here was a much longer post on the topic:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=130036
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1735142
Here was a much longer post on the topic:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=130036
Originally Posted By: CELICA_XX
There is no way it counts engine revs...
Perhaps you could read the thread that the other poster put up first? (thanks Nate)
I can tell you it does indeed, and many other parameters are used as well...
There is no way it counts engine revs...
Perhaps you could read the thread that the other poster put up first? (thanks Nate)
I can tell you it does indeed, and many other parameters are used as well...
Last edited:
Originally Posted By: ram_man
OK so I'm skeptical of this system. My question is how does it work? It says I can go up to 10,000 miles on my focus before a change. How does it decide that? Does anyone have an olm that they listen to and have clean engine pictures to prove it's accuracy. I am nervous about 10,000 oci with a syn blend and a motor craft filter. ....am I just living in an old way of thought. I plan on keeping this car a very long time.
This is how it would work in my vehicle if it were on it;
Put a pc. of tape over the OLM. Change the oil as you had done before an OLM came along. Simple.
OK so I'm skeptical of this system. My question is how does it work? It says I can go up to 10,000 miles on my focus before a change. How does it decide that? Does anyone have an olm that they listen to and have clean engine pictures to prove it's accuracy. I am nervous about 10,000 oci with a syn blend and a motor craft filter. ....am I just living in an old way of thought. I plan on keeping this car a very long time.
This is how it would work in my vehicle if it were on it;
Put a pc. of tape over the OLM. Change the oil as you had done before an OLM came along. Simple.
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