I want to drain the factory fill and change the filter on my new Mazda CX 5 with the 2.5 liter Turbo Skyactiv engine somewhere around the 1000 - 1200 mile mark and refill with a quality synthetic. I think the Castrol Edge will be a good match for this engine. I have 3 quarts of Redline 5W-30 leftover from my supply for my previous Nissan 370Z that I would like to consume. Any issues with mixing 3 quarts of the Redline and 2 of the Castrol Edge of the same viscosity and running until the next change and then refilling with Castrol Edge for the regular OCI's ? The dealer offered me a free oil & filter change at 7500 miles but I don't want to run that long on the factory fill and who knows what kind of bulk 5W-30 they will use for the free change.