Our highest mileage car that saw 99% highway everyday had oil changed at the longer of the two intervals(12000km/7500miles) for the first 300 and something thousand km. Once it got around 400 and was used only in the city I changed it more often at 6000km/3700miles like the rest of the ones in the fleet. Basically if you live in Canada and use the car like a car you need to follow the severe schedule according to the manual.
If it ever warms up here I'm gonna pour some thicker oil in my personal 2014 Mirage when I change it(or next time it's low) to see if it'll shut up the rattling engine. I've got some 5w40 and a bunch of gear oil to try. I've basically got no engine warranty as I have no proof of previous service history so I'll keep it going til it starts using more oil than gas or get louder than the radio.
My mom says I'm cool
View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 35.5 mpg (US) ... 15.1 km/L ... 6.6 L/100 km ... 42.6 mpg (Imp)