I use the Flying J at London...it will be the exit immediately after Wellington Rd (assuming you are still East bound) and can be a bit of a surprise if you are not ready as the sign is rather well hidden. They move a LOT of fuel and are definitely the cheapest you will find. If all goes well you should make Collingwood and back on one tank. Here in the Sarnia area (at the Cdn end of I94 and I 69, and across the Bluewater bridge, I use the Petrocan cardlock...but that is of no use to you. If you happen upon a BUSY Sunoco station with Sunoco Gold Diesel (min cetane 47) you will find that the IH engines really like the change....quieter and smoother!
Safe trip.
Ian
Safe trip.
Ian