What % synthetic is the synthetic blend? I have seen numbers ranging from 15% to 60% tossed around the 'net, but nothing definitive. I am approaching 2000 miles on my 2012 F250 and am wanting to change it real soon. My plan is to buy a 5qt Motorcraft jug of 5-20 Synthetic Blend from Walmart and 2qts of Motorcraft full synthetic from Pep Boys plus a Motorcraft filter. This July I will be towing my travel trailer to west Texas and want to change the oil before then.