Doug, I have not made any Chilean wine however my Merlot, Cab. Franc and Cab. Sauv. from California I oak probably more than many others. I use 8 ounces per 5 Gallon Carboy. I'll use an American medium toast (no butter) and bulk age it 10 months.
We like the oak taste and this amount still allows the grape flavor to come thru. My other red wines I'll oak half as much. If you'd like I'll meet you and give you a bottle of our Merlot to taste. Two years ago I didn't make a Cabernet and last year I made both Cab. Sauv. and Franc but they are still aging.
I'm anxious to hear what the others here do. Often thought about an oak poll for the big reds.