Today the "change oil soon" light came on in my Buick after about 3,300 miles and 3 months since the last oil change. Looks like the oil life monitor may be pretty accurate after all. Most of the 3,300 miles were short in town trips to and from work plus other short around town jaunts of less than 5 miles in weather typically 30deg F or less. Only about 800 miles of the 3,300 were long distance high speed interstate driving. 3K to 3.5K miles is about how long I would normally leave in a conventional oil under those driving conditions... so at least for now it appears that GM did a good job at getting the algorithms correct and setting the penalty factors for cold start ups as they should be. I'll be crawling under the car tomorrow to change out the Havoline Synth in there. And yes I know the OLM is set for conventional oils, but I figure that so long as I change the synth out when the monitor says it is time to change out dino oil, I'll be way ahead of the game in terms of having oil in the crankcase that still has some life in it and will protect the engine very well.