[mountie]

Originally Posted by 68 50th

Thanks for the reply Mr_Rich,

I have it in my 2001 GMC 1500, 5.3 gas engine and I read GM introduced it in 1988 in some vehicles:
https://assets.cobaltnitra.com/teams...145efa6b30.pdf

That is why I wonder if it ever came in any 88-98 trucks.

In the link, it says," What if my oil has gone 6,000 miles, the light doesn't turn on, & still looks ok, or is looking dark...."
Response, " ..."Different driving conditions will change required oil change.." (( paraphrased ))

THAT IS NUTS....... The GM "monitor" can not compute the chemical makeup in the used oil. OR THE FILTER CONDITION. Oil will break down & dilute, even if it's not dark "looking".

3,000 to 5,000 miles.... change it. And filter too.
I learned this from one of the best record-holder engine tuners in the country. ( He sends oil to a lab for testing)

I would never put total trust in an idiot light or an algorithm.

But, after my opinion...... I didn't know a truck as old as mine would have one.