hey guys! in my 6.0l v8 vortec engine im at 250,000km and want to run a hm oil to see if it will stop the leaks i have. right now its summer and we are regularly above 20 celcius everyday and can get into 30celcius +. i dont run high oci at all, i usually just go by the 6000km sticker or the OLM but i still prefer to run a syn oil for piece of mind. i cant seem to find valvoline full synthetic maxlife in canada, i could only find the red bottle which i believe is conventional 1. Mobil 1 High Mileage Full Synthetic Motor Oil 5W-30 2. Pennzoil 5W30 Platinum Synthetic High Mileage Motor Oil 3. Quaker State 5W30 High Mileage Synthetic Engine Oil 4.Royal Purple 5W30 Synthetic High Mileage Motor Oil these seem to be all the ones i can find in canada, correct me if i am wrong please so which would be the best? or do i basically get whats on sale? i noticed that the pennzoil and the quaker state is usually on sale but i dont remmeber ever seeing mobil hm or royal purple hm on sale thanks!