GM Oil Life Monitor question.

[axjohn]

Don't know which forum to put this one in.

My cousin recently visited me with her new (5 months old GMC SUV (Yukon), which now has 16,000 miles on it. The oil life monitor indicated "0% life" while we were driving to dinner.

Question. Anyone have any experience with these monitors, and how accurate they are? What would the danger be of driving with the oil life below, say 25%, 10% etc?

She wanted to wait until the next day to get the oil changed, in her city (approximately 70 miles away). I have no experience with these systems.

What would adding a little Lube Control do under such conditions? Anything? Can Lube Control be used in vehicles with oil life monitors, and does it interfere with the monitors readings. Would one of these vehicles be able to run the oil longer IF Lube Control was used from the beginning of the oil change cycle? Would adding LC once the oil life monitor read "0" change the reading?

Thanks in advance.

 

[Pick]

axjohn, the GM Oil Life Monitor is a computer program that adjusts the "Oil Life" percentage based on many parameters, including time, trip duration, temperature, etc. It does NOT actually analyse the oil in the crankcase. Once it is started back at 100%, the clock starts ticking, so to speak. A lot of time and research has been spent on making the system accurate.

That being said, I am running my wifes 2004 2.2L EcoTech powered Malibu on Amsoil 5W30, and plan on changing the oil at 0%. It is reading about 24% as of yesterday at about 7500 miles.

I forgot to reset it on my Duramax with my last change to Rotella T Syn 5W40, so I will just change it out at 7500 miles, or so. It has gone over 10K before reading "Change Oil" in the past. I have the dumb system on my truck, it does not read percentage, just tells when it needs to be changed.

 

[davefr]

GM's oil life monitor is a wonderful system that uses multiple parameters to estimate oil life. The only thing more accurate is a UOA.

I'm amazed at all the GM owners that ignore this technology and rely on the Jiffy Lube commercial or Grandpa's "color rule" to determine when to change oil!!

If you think GM is overly conservative then just pick whatever percentage you want as a guardband. For me it's about 20%.

Having said that, you're safe getting an oil change at the next convienant point. Oil life is a continuous degradation. Nothing tells the oil to instantly turn to coal when GM says's it's life is over.

 

[haley10]

The GM OLM is based on calculations and doesn't know if you use LC, synthetic oil, etc. It can't check for dust and silicon in the oil.

LC may extend oil life by helping to keep insolubles in check when used as directed. It will not restore an oil when the OLM has determined that the additive package is depleted.

 

[LarryL]

Does this monitor snitch you out to the dealer if you go past zero? And if you have one of these have you cross checked it with TooSlick's formula?

 

[TooSlick]

Larry,

Let's keep this low key ...I don't want a couple of GM thugs coming down from the Motor City to wack me, as I'm getting in my imported Audi TT roadster...

"Tooslicks Formula" sounds like something I should be selling out of a gypsy wagon. LOL!

Is the GM system vehicle and engine specific? If not, then it's pretty crude (oh heck, there I go again) What they really need is an in-situ diaelectric sensor, nanosized brookfield viscometer and auto titrator - now thats a suite of sensors I could support! (of course it would cost as much as the engine)

Tooslick

 

[k1xv]

The GM oil monitor does not analyze the oil. Rather, it keeps track of a few parameters that may affect the remaining oil life, such as number of engine starts and total engine revolutions since the last re-set. As noted above, it does not know what kind of oil you are using, whether you changed the filter, etc.

In my 2003 Duramax, with Shell Rotella synthetic, I change when the remaining life indicates about 35%.

If you do not reset the indicator at an oil change, it does not know the oil has been changed. So, I wonder if somebody forgot to reset the indicator on your cousin's Yukon.

 

[AndyH]

quote:

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Originally posted by TooSlick:
Is the GM system vehicle and engine specific?

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According to that GM engine engineer who posted here a while back, it is calibrated for each vehicle it's used in.

Here's the message thread:
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=1;t=010523

And here's his quote:

quote:

---

"It {the oil life monitor} 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."

---

 

[kenw]

"calibrated for each engine" is a whole lot different than "for each vehicle".

In other words, the 3.8L gets the same calibration formula regardless it being in a Buick, Pontiac or Chevy.

The 3.1L has the same calibration regardless of which vehicle Model/Brand it gets plugged into, etc.

which makes sense.

 

[Mike_dup1]

My 2005 CTS manual says to change oil within 600 miles after it says to change oil...

I am not a big fan if using oil additives and if she reads the owner manual GM recommends against it.

Also, just because its says 0% remianing does not mean a crisis.

[ May 25, 2005, 09:08 AM: Message edited by: Mike ]

 

[AndyH]

quote:

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Originally posted by kenw:
"calibrated for each engine" is a whole lot different than "for each vehicle".

---

Agreed, looks like I misspoke (although I didn't have time to re-read his entire message and all the follow-up).

 

[segfault]

quote:

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Originally posted by Mike:
Also, just because its says 0% remianing does not mean a crisis.

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Right, the GM engineer that used to post even indicated that in some cases, you might be able to go twice the distance indicated by the OLM before the ZDDP in the oil was depleted.

At 16,000 miles, I am guessing that this is the second oil change on the Yukon? I think the upper limit for the OLM is either 12,500 miles or 15,000 miles.