Who uses their OLM anyway.
Me :), though it's set up for conventional oil (I phoned GM Canada when I bought the car) and I use Mobil 1. Occasionally I reset it and continue on before dumping the old oil (but not in winter).
The OLM appears to be accurate. It winds down faster in winter than it does in summer. A few summers ago it registered in the 20-per-cent range after about 1,500 kilometres of city and country driving, then a trip to Vancouver and back to Winnipeg — 4,600 kilometres return, plus driving in Vancouver. It wound down to zero per cent at almost 12,000 kilometres (calibrated for dino, as mentioned).
Without the OLM I would have changed the oil long before. I was tempted not to, but figured what the hey.