I signed up for the forums here because I have been reading these posts for days and like the title says WOW. Im still as undecided as I was at the beginning. I have changed my own oil for years and always just went with conventional. Usually castrol but then when times were tight store brands and usually from filters. I have now got to a point in my life that I have 2 fairly nice cars for me, one was just bought a couple weeks ago so thus the research started. My wife has a 08 grand caravan that I usually do Castrol. And I now have a 04 f150 supercrew. I'm going to do hers next couple of days because its time and mine because I am unsure of when it was done last. So should I just stick with conventional or do them both blended or full synthetic? If I do a full synthetic will a wix filter be fine with it? Any info and direction from the oil gurus here would be much appreciated. Thanks ahead of time.