oil change
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
E-T who was involved in the design of the car posted a great summary of the oil life monitoring system. It really is avery clever system and took years to develop. Seems a shame to ignore it IMHO. I've copied the explanation below.
FWIW, I normally hit 1 year before 0% nowadays. When the car was a DD I'd get up to 10k from my oil
In short, its your car and many feel happier doing old school oil changes. With synthetic oil and the OLM system it really is a waste of $$$. HTH
Oil Life Monitoring
Courtesy E-T
Here is how the OLM system works..
Mileage has little to do with how oil is monitored, here is the idea:
Car 1:
If you drive 90% of the time on the highway lets say 1500 rpm an hour.
you engine sees 90,000 revolutions in that hour and you drive 60 miles.
Car 2:
If you drive around town, profiling with 90% of your driving in 1st, 2nd, and 3rd gear, taking 4,000 rpm on average. That's 240,000 revolutions of the engine in 1 hour and you only drive 30 miles.
Taking this out to 3 months , 90 days:
Car#1 3,600,000 rpms and 5400 miles
Car#2 21,600,00 rpms and 2700 miles
This represents 1 hour of driving a day for 90 days.
Car #2 sees 6 times the engine duty of car #1 and Only half the mileage
So you can see that mileage can be very misleading. Considerations are: Starts, Cold starts, oil temp over time, rpm, mileage, engine coolant temp, load, knock sensor feed. Calculations are used to decrease the oil life percentage from the baseline.
FWIW, I normally hit 1 year before 0% nowadays. When the car was a DD I'd get up to 10k from my oil
In short, its your car and many feel happier doing old school oil changes. With synthetic oil and the OLM system it really is a waste of $$$. HTH
Oil Life Monitoring
Courtesy E-T
Here is how the OLM system works..
Mileage has little to do with how oil is monitored, here is the idea:
Car 1:
If you drive 90% of the time on the highway lets say 1500 rpm an hour.
you engine sees 90,000 revolutions in that hour and you drive 60 miles.
Car 2:
If you drive around town, profiling with 90% of your driving in 1st, 2nd, and 3rd gear, taking 4,000 rpm on average. That's 240,000 revolutions of the engine in 1 hour and you only drive 30 miles.
Taking this out to 3 months , 90 days:
Car#1 3,600,000 rpms and 5400 miles
Car#2 21,600,00 rpms and 2700 miles
This represents 1 hour of driving a day for 90 days.
Car #2 sees 6 times the engine duty of car #1 and Only half the mileage
So you can see that mileage can be very misleading. Considerations are: Starts, Cold starts, oil temp over time, rpm, mileage, engine coolant temp, load, knock sensor feed. Calculations are used to decrease the oil life percentage from the baseline.
Last edited by DeeGee; Dec 10, 2009 at 10:10 AM.
Race Director
Joined: Aug 2003
Posts: 16,270
Likes: 30
From: "It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-‘18-'19
NCM Sinkhole Donor
E-T who was involved in the design of the car posted a great summary of the oil life monitoring system. It really is avery clever system and took years to develop. Seems a shame to ignore it IMHO. I've copied the explanation below.
FWIW, I normally hit 1 year before 0% nowadays. When the car was a DD I'd get up to 10k from my oil
In short, its your car and many feel happier doing old school oil changes. With synthetic oil and the OLM system it really is a waste of $$$. HTH
Oil Life Monitoring
Courtesy E-T
Here is how the OLM system works..
Mileage has little to do with how oil is monitored, here is the idea:
Car 1:
If you drive 90% of the time on the highway lets say 1500 rpm an hour.
you engine sees 90,000 revolutions in that hour and you drive 60 miles.
Car 2:
If you drive around town, profiling with 90% of your driving in 1st, 2nd, and 3rd gear, taking 4,000 rpm on average. That's 240,000 revolutions of the engine in 1 hour and you only drive 30 miles.
Taking this out to 3 months , 90 days:
Car#1 3,600,000 rpms and 5400 miles
Car#2 21,600,00 rpms and 2700 miles
This represents 1 hour of driving a day for 90 days.
Car #2 sees 6 times the engine duty of car #1 and Only half the mileage
So you can see that mileage can be very misleading. Considerations are: Starts, Cold starts, oil temp over time, rpm, mileage, engine coolant temp, load, knock sensor feed. Calculations are used to decrease the oil life percentage from the baseline.
FWIW, I normally hit 1 year before 0% nowadays. When the car was a DD I'd get up to 10k from my oil
In short, its your car and many feel happier doing old school oil changes. With synthetic oil and the OLM system it really is a waste of $$$. HTH
Oil Life Monitoring
Courtesy E-T
Here is how the OLM system works..
Mileage has little to do with how oil is monitored, here is the idea:
Car 1:
If you drive 90% of the time on the highway lets say 1500 rpm an hour.
you engine sees 90,000 revolutions in that hour and you drive 60 miles.
Car 2:
If you drive around town, profiling with 90% of your driving in 1st, 2nd, and 3rd gear, taking 4,000 rpm on average. That's 240,000 revolutions of the engine in 1 hour and you only drive 30 miles.
Taking this out to 3 months , 90 days:
Car#1 3,600,000 rpms and 5400 miles
Car#2 21,600,00 rpms and 2700 miles
This represents 1 hour of driving a day for 90 days.
Car #2 sees 6 times the engine duty of car #1 and Only half the mileage
So you can see that mileage can be very misleading. Considerations are: Starts, Cold starts, oil temp over time, rpm, mileage, engine coolant temp, load, knock sensor feed. Calculations are used to decrease the oil life percentage from the baseline.
Bottom line is with today's synthetic oils, it isn't neccessary to change oil every 3K miles.
Personally - I have three cars that all have OLM's, all three use synthetic oil as a factory fill, and all three use more than 6.5qts., so if I changed oil every three months or 3K like in the old days, I would be changing oil (expensive oil) all year long.
As Dave pointed out - a lot of engineering went in to making the OLM a valuable functional tool, instead of a gimmick. I follow the OLM, and I change my oil basically once a year.
BTW - I had a brief PM correspondence with E-T about a week ago, and for those interested, he's doing great.....and he is by his own admission, more mellow! I really miss having him around all of the time......
Safety Car
Joined: Nov 2000
Posts: 4,419
Likes: 6
From: Arroyo Grande CA
Here's a GM Oil Change calculator.
http://www.gmols.com/index.htm
Click on Implementation Tools on the top bar.
Go down to Additional Tools.
Click on Engine Oil Life Predictor (.xls)
I put my stats in and it predicted 7561.38 miles from my last change to the next. I'll see how accurate it is a little later, according to the OLM.
http://www.gmols.com/index.htm
Click on Implementation Tools on the top bar.
Go down to Additional Tools.
Click on Engine Oil Life Predictor (.xls)
I put my stats in and it predicted 7561.38 miles from my last change to the next. I'll see how accurate it is a little later, according to the OLM.
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Drifting
Joined: Feb 2005
Posts: 1,643
Likes: 167
So what if the car sits for a long time, is that wearing out the oil? If a car sat idle for an entire year since its last oil change, would you change the oil again just because a year had passed?
Last edited by thisMSGgood4me; Dec 10, 2009 at 02:57 PM.
Drifting
Joined: Feb 2005
Posts: 1,643
Likes: 167
What's magic about 1 year (other than that's what the owner's manual says)? What's your OLM down to after 5200 miles?
Last edited by thisMSGgood4me; Dec 10, 2009 at 02:59 PM.
Race Director
Joined: Jan 2006
Posts: 10,554
Likes: 33
From: Not on either liberal coast.
I think the "one year" option was so owners just don't totally forget to do the oil/filter preventative maintenance. Most "enthusiasts" won't let that happen. Many "owners" (there is a difference) might. Hell, some don't even know how to find their DIC.
If in doubt, have the oil analyzed. Personally, I have a difficult time believing that oil is still good at 364 days, but not at 366 days.
Le Mans Master
Joined: Feb 2009
Posts: 5,253
Likes: 9
From: Northwest CT
Someone correct me please if I am wrong.
Drifting
Joined: Feb 2005
Posts: 1,643
Likes: 167
Condensation is not dependent on whether the oil is new or not. It's the environment which the car is in (as you pointed out).
Drifting
Joined: Feb 2005
Posts: 1,643
Likes: 167
Conventional wisdom for what seemed like forever was 3000 miles or 1 year, whichever came first. Now the 3000 mile part of the equation has gone by the wayside, with advances in oil and engine technologies. So is the other part of that conventional wisdom also out-of-date? Something to think about.
Team Owner
Joined: Jun 1999
Posts: 41,793
Likes: 153
From: Houston,Texas USA
Safety Car
Joined: Sep 2005
Posts: 4,062
Likes: 103
From: Southeast, Tennessee
St. Jude Donor '09 thru '26
Use the oil life monitor function unless you drive so few miles the oil would be in the car over a year. Then I would change it at least once per year. IMHO it's not a good idea to just let the contaminents that end up in the oil sit for more than a year.
