Before I knew better, I bought a 5qt jug of Syntec 10W30, which I finally decided to use up last oil change on my winter beater. Problem is that I happened to get a crappy SuperTech Filter with a Anti-drainback valve that didn't work (I got to watch the gauge stay on the peg way too long on each cold start). Anyway, so at 2,000 miles into what I planned as a 4-5,000 mile interval, I swapped filters, and accidentally bout 5W50 to top up with. Are the additives in different wieghts of US Syntec compatible? Can I just assume that I can safely run this mixture for another 2,000 miles?