GM OLM questions...

[crw]

I have a 2000 Suburban, with the oil life monitor that doesn't show a % remaining... it just lights up when it thinks it's time for a change.

I used to stick to a 3 to 4K OCI. Then, after reading stuff here, I thought I'd rely on the OLM. So I changed my oil (based on my OCI schedule) then did the proceedure to reset the OLM. BUT, the OLM wasn't showing "change oil soon" at that time... it was somewhere inbetween.

So now, after only 1 to 2K miles, the OLM comes on! My question is, does the OLM need to come on (showing "change oil soon") before it can be reset? Or can it be reset at any time? Nothing was severe with my situation except that we're going through a typical Idaho winter (cold temps).

Oh, and by the way, I have no owner's manual for the vehicle. It was used, and of course for most owners, the manual is the first thing to be tossed as it takes up valuable space in the jockey box.

 

[The Critic]

The OLM CAN be reset before the "Change Oil Soon" message comes on. 1-2K between drains is perfectly normal under severe service (i.e. harsh temperatures) with the OLM, which is why it is sometimes better than going the 3mo/3K route.

The important question is whether or not the Driver Information Center read "Oil Life 100%" for a brief moment after you reset the system last time.

 

[thooks]

That is NOT an Oil Life Monitor on that 2000 5.3L engine.

It counts the number of revolutions the engine has seen since it was last reset.


I changed the oil in mine about every 3500-4000 miles. The "Change Oil" would come on about every 6000 miles.

 

[crw]

Hmmm... I never notice it saying "Oil Life 100%", I've never seen it.

If the OLM did work properly, I'm surprized that it factored in so much for the cold. Well, we're usually between 10 and 30 F for overnight temperatures.

 

[crw]

I'll have to try it again,... maybe I didn't get it done right the last time.

 

[Rhymingmechanic]

Here's the procedure for resetting the OLM on a 2001 Silverado:

Turn the key to "run." (Don't start the vehicle.)

Pump the accelerator 3 times within 5 seconds.

"Change Oil Soon" should flash several times to show the system has been reset.

 

[brianl703]

That procedure works for any GM vehicle with the oil life monitor..including those which only have it as an "undocumented feature" accessable only with a scantool (which will show the OLM % remaining).

 

[The Critic]

quote:

---

It counts the number of revolutions the engine has seen since it was last reset.

---

Which is part of what an oil life monitor is supposed to do. It is based on ZDP depletion, but engine revolutions, oil temps, soak times, trip lengths, etc are all modifiers of the curve.

GM doesn't have any "mileage counters" in their vehicles, unlike the ones Toyota and Ford have. Any GM vehicle that has the oil life monitor is indeed an oil life monitor and NOT a mileage counter.

 

[TomJones76]

Based on what you just described, you reset the OLM properly, and the vehicle really did tell you it really thinks it needs an oil change when that light came on.
I would be VERY curious to hear how you drive that truck. Towing? Long idling on a construction site? Commuting to work in stop and go?

 

[The Critic]

Someone told me that their GM minivan went 1800 miles between an oil change, per the OLM in the winter. (Not on this forum) Driving style consisted mainly of 1 mi trips, lots of idling, in the 0-20F (?) winter.

I think Audi Junkie had a relative who went 2200 miles between an oil change per the OLM on their Pontiac Minivan as well, and he posted about it somewhere in Car/Truck Engine Oil.

 

[lewk]

brianl703 is this an undocumented feature on 97 astro vans w/ the 4.3l vortec, or is it available as a flash upgrade to the prom?

 

[brianl703]

I'm not sure. I wouldn't expect it to be on a '97 model, but maybe there is a possible flash upgrade that will add it, if GM ever added the OLM to the Astro with that same PCM hardware. Of course the Tech II tool may not allow it to be flashed in.

It is an undocumented feature on the 2004 Malibu Classic (N-body with the Ecotec engine). I use OBD II Vehicle Explorer by Alex Peper to access it.

 

[TonyMazz]

The OLM is based on engine revolutions, and sustains a "penalty-factor" for conditions that indicate that the oil temperature is not upto proper temp (i.e. steady state, thermostat open).

Essentially (steady state i.e.195 / current temp) where as the cold temp will be less than 195 hence the penalty factor will be greater than 1 hence the revolutions will be 1 X penalty factor....

That said, the revs will add up substanially because GM has determined that cold / or oil below temp i.e. short trips never quite get to temp and burn the moisture off, thus adding to conditions that decline the effectiveness of the oil....

 

[crw]

At this point I don't know if it got reset properly
or not. I guess it stands to reason that the
computer is in fact taking into account our winter
and my wife's frequent taxi service for our five
kids... maybe it's working and I need to think about
an oil change.

 

[TomJones76]

---brianl703
I'm not sure. I wouldn't expect it to be on a '97 model, but maybe there is a possible flash upgrade that will add it, if GM ever added the OLM to the Astro with that same PCM hardware. Of course the Tech II tool may not allow it to be flashed in.
----

My '96 Caprice had it, so they DID offer it on at least some cars back then.