Thanks!
I feel more at ease after reading your posts, D911 and nelbur. I'm definitely going with a stop leak product.
Which one should I use? Not all products are available in Canada. I found something called Rislone which seems to be manufactured by the same guys that make Bars leaks. Is that ok? The head gasket repair product is here: http://www.rislone.ca/catalog/view/38-head-gasket-fix-31111
And they have a radiator stop leak here:http://www.rislone.ca/catalog/view/40-liquid-aluminum-cooling-system-stop-leak-31186
I hear some people use a Prestone product, but I'm not sure they have it in Walmart here in Canada.
Worst case, if the product you guys recommend is US-only, I can always drive south of the border and grab it. It's only an hour and a half drive.
Update: I just checked the oil level following a longer highway trip. (about 80km each way), and the level is definitely up. So it's pretty clear where my coolant is going.