GM oil life monitor (redux)

[Forkman]

Today the "change oil soon" light came on in my Buick after about 3,300 miles and 3 months since the last oil change.

Looks like the oil life monitor may be pretty accurate after all. Most of the 3,300 miles were short in town trips to and from work plus other short around town jaunts of less than 5 miles in weather typically 30deg F or less. Only about 800 miles of the 3,300 were long distance high speed interstate driving.

3K to 3.5K miles is about how long I would normally leave in a conventional oil under those driving conditions... so at least for now it appears that GM did a good job at getting the algorithms correct and setting the penalty factors for cold start ups as they should be.

I'll be crawling under the car tomorrow to change out the Havoline Synth in there. And yes I know the OLM is set for conventional oils, but I figure that so long as I change the synth out when the monitor says it is time to change out dino oil, I'll be way ahead of the game in terms of having oil in the crankcase that still has some life in it and will protect the engine very well.

 

[Stewart Fan]

I was leary of using it in the past,but it seems to work well. My truck is a 2500HD with the 8.1 liter Vortec. The light came on at about 3300 miles,which is just a bit more than I'd change at anyways. I also use synthetic oil (M1 10-30). I tow alot with my truck,and also use it for alot of short trips. Probably 75-80% of my driving is less than 10 miles at a time.

I'm going to continue to use it,now that I know its pretty accurate.

 

[JohnnyG]

Actually, it depends on the model year of your vehicle and engine design to an extent. For example, the 1999 Northstar had a MAX oil life of about 8000 miles. Due to the cam follower redesign in 2000, the oil life MAX was extended to about 12,000 miles, all on dino. Don't quote me on the EXACT numbers, but you get the idea. So you can see that even though GM considered more factors than you would normally expect, some people would be unhappy using the OC indicator. It just would not fit with their idea of "correct" OCI's.

 

[scooter996]

Its based off mileage just like Mercedes Benz monitor. For some reason people think theres alittle man in a lab coat behind the dash board sampling the oil and when it goes bad he turnson the light. According to the owners manual convential oil should be changed at 7,000 miles. I change my synthetic with sampling at 15,000 with no problems.

 

[dickwells]

Don't forget that if you read the manual it will say change oil within the next 2 tanks of gasoline. This leaves quite a little margin.

 

[Bamaro]

quote:

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Originally posted by scooter996:
Its based off mileage just like Mercedes Benz monitor. For some reason people think theres alittle man in a lab coat behind the dash board sampling the oil and when it goes bad he turnson the light. According to the owners manual convential oil should be changed at 7,000 miles. I change my synthetic with sampling at 15,000 with no problems.

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Actually, its a little more involved than simply going by mileage. Check here for a description on how it works:
http://www.gm.com/company/gmability/environment/gm_and_the_env/releases/oillife_monitor_041603.html

 

[JohnnyO]

The ones on my wife's Grand Am and my mom's Cadillac seem pretty accurate IF you're using dino oil. I put syn in both but change every 5k in wifey's car and every 6 months in mom's Caddy. The syn is probably good for longer but I change it out anyway.
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=001164

 

[Titanium_Alloy]

On my 2002 Grand AM Ecotec I go by oil life monitor and use syntetic oil (Mobil 1 right now). I know it would've been fine with dino, but I like to have a safety margin. I might extend drain interval with syntetics 1-2k miles past the interval indicated by a light, but it's not the case for me since I drive it now only 3k/year. Thus I try to change oil every 10-12 months. By the way when light goes off it indicates that oil life left is under 10%, so there is a significant margin especially if you use synthetic oil.

Regards,

 

[Patman]

FWIW, the 1997 to 2000 Corvettes have their oil life monitor set for 10,000 miles max, and countdown from there, while the 2001-2004s are now set to 15k max, and countdown from there. A lot of guys drive so hard though, that their oil life gets down to 0% by around 5 or 6k.

 

[VaderSS]

Well, I've been using that light to get a weighted average on my intervals. Just realized with 9000 miles on the ticker that the light was burned out. Mine has a MAX interval of 7500 before it lights up. OOPS! Before anyone asks, no I did not get that one analyzed. I was 500 miles from home when I noticed it, so I went straight to the nearest Walmart and got it drained.

 

[DEWFPO]

Our 2003 Audi Bi-Turbo has a 10,000 OCI computer that counts backward as well. It came on at 8,800 miles the first time instead of 10,000. Many cold starts, lots of fun mountain driving.

DEWFPO

 

[DEWFPO]

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[ January 14, 2004, 07:49 PM: Message edited by: DEWFPO ]

 

[Patman]

quote:

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Originally posted by VaderSS:
Well, I've been using that light to get a weighted average on my intervals. Just realized with 9000 miles on the ticker that the light was burned out. Mine has a MAX interval of 7500 before it lights up. OOPS! Before anyone asks, no I did not get that one analyzed. I was 500 miles from home when I noticed it, so I went straight to the nearest Walmart and got it drained.

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I've been waiting for your next UOA from your LT1, and a 9k run would've been very informative!

 

[VaderSS]

Next on will be a Pennzoil 10W30 to 4k. Should not be more than 2 months...

 

[Forkman]

quote:

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Originally posted by scooter996:
Its based off mileage just like Mercedes Benz monitor. For some reason people think theres alittle man in a lab coat behind the dash board sampling the oil and when it goes bad he turnson the light.

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No one here is under that impression. In the GMs at least it is based off of counting down from a set number of engine revolutions and has nothing to do with mileage. Penalty factors are included such as number of cold starts (based on coolant temp/oil temp) that take off more "ticks" on the countdown timer.

 

[sHERM]

I have a 2000 pontiac Bonneville with a oil life monitor in the on dash computer. I think it works great. When I used to drive it for work I put a lot of highway miles and it would extend to almost 10k. Now that my wife drives it with short trips it goes to only 7500k.