ANy time you change the oil, if you want to rely on the oil management system, reset it when you are done.
I change my oil between 3000-5000 miles (running conventional in all my cars). I don't like trusting the oil light (too many factors can throw it off, like disconnecting the battery).
In the case of the Monte, I park it in the winter, before I fire it up for summer, it gets an immediate oil change (regardless of the miles on the oil). Sitting that long, the crank case may have moisture from condensation, any crud from the motor has settled to the bottom. Just good practice.

 

Put a PF52 sized oil filter on it. It is the same threads but is longer. Makes it much easier to reach from the top or bottom plus other added benefits.

An easy car to look up for filter cross reference is either the 1995 Monte with a 3.4 DOHC or 1998 Blazer 4.3L