Our 1998 Buick LeSabre actually had a reset button in the glove compartment
area.
There were occasions it came on at less than 3500 miles, but not often.
My son told me that he has been resetting it when he changes oil, but
has also changed the oil before it came on, because we about to take a
long trip. And if it isn't on, he doesn't reset it.
That raises some questions. Personally, I don't see it as useful
unless you're willing to let it be your sole guide to oil changes.
Since we jot down mileage at changes, then change again after 3k miles
and no later than 4k miles, the light is just an irritation.
I have heard the GM algorithm strongly defended as far as its ability to
predict
oil change intervals, but like most everything else in this entire thread,
there is
no hard proof that I have ever seen.
Agreed. If I feel like it later, I'll take a look at the shop manual
to see if says anything about it. Don't hold your breath.
I am sure these studies must exist, on filters, oil change intervals, effect
of
particulates of different size distributions in the oil, etc etc, but I have
never
seen them. (And I HAVE looked for them)
I don't think they exist in a useful form. Imagine the logistics and
expense of testing so many engines under many conditions and miles,
with controls.
Even if one were to test the oil filtration characteristics of many
filters, using one engine to do it would not necessarily reveal how
another engine would do with the same filters.
Then you'll naturally get mechs and internet pundits saying stuff like
"Sure, the Fram might be OK the Chevy, but the Ford really needs a
Purulator."
The CR report was the most extensive I've seen, but had many flaws.
I consider it useless except as an interesting read.
The auto manufacturers have the best somewhat controlled ability to
get a handle on it with their maintenance schedules and dealership
networks. Besides that, when I worked at IH there were engines
constantly running on stands in the engine test area, and I'm sure all
manufacturers do the same.
I don't know what tests they do, but it's a safe assumption they are
using their own oil change recommendations to run some amount of
miles, teardown, and look for wear.
Doubt they tinker too much with the oil beyond that.
And as far as I saw, testing was done under constant external air
temperature.
Could be wrong about that though.
As an aside, when I was at IH in Melrose Park, IL, an engine test tech
was killed when an engine flew apart. There was quite a stink with
the UAW about flawed test equipment that allowed the engine to go full
throttle. About 1973.
In any case, a car on the road, driven under diverse weather
conditions, and varying warm-up and acceleration modes, is best left
to the owners own judgement regarding when to change the oil.
My opinion.
--Vic