My daughters each have a 2007 Civic, and I HAVE done oil analysis a couple times. I use Castrol GTX 5w-20 and it's been good with the maintenance-minder. The 2 of them have different driving habits, and their oil change intervals come up different. But the analysis says I could have gone another couple thousand miles.

One of those analyses was done after letting the monitor go all the way down to zero% & 100 miles beyond. (Did you know that after it gets to 0% it counts miles rather than negative percentage?) Even that one had some TBN left.

Oil change intervals were pretty conservative before the monitors. They had to assume the worst possible abuse. Hammer the gas pedal immediately on a cold start, or go 20% beyond the mileage because you just get busy for a few weeks. Those of us who take care of our cars don't treat em like that anyway.

Having said that, the oil-life monitor can't allow for the engine getting real old. If it loses compression and starts putting a lot more combustion products into the oil, I can see where the monitor would no longer be conservative.