Now of course oil substance matters much more than a label, but I'm curious to hear other opinions. In my old Nissan Sentra I used Valvoline MaxLife oil and had great results considering the condition and age of the vehicle. Now that I have a Mazda 3 with only 3,000 miles, I would like to start the car off right with proper maintenance. One of these categories of maintenance I'm debating on is oil. I understand that the Mazda manual suggests Castrol 0W-20 oil, but does it truly make a difference if I use Valvoline 0W-20 instead since I've used it in the past with success? Thanks in advance.