2005 trailblazer 4.2 installed factory oil sender above oil filter, gauge not goes to 80 lbs after driving for 40 min . i performed gauge sweep with scanner looked like worked correctly. i have read that steeper motors in clusters are bad, any info would be helpful.

So your saying, the oil gauge shows 80 psi at startup, and then after driving awhile, the gauge goes down to...what?

And when was the last oil change?