Full synthetic is the only way to go. I'm a bit overkill, but I run a winter front to block the cold air from radiators. IMO, does 2 things. 1. Keeps the air from getting to rads. 2. Keeps whatever stuff (rock salt/stones etc) from getting into rads. Work is only 15-20 minutes away so I want to be able to get it up to full operating temps both ways or perhaps a tad higher. Without stones, rock salt etc from getting to rads helps keep possible holes from occurring, aid in not plugging the holes in rads, and lastly, perhaps help keep things from rusting out. During summer months, I run a full bug screen front to keep bugs out of rads. When I got rid of my '03 F250, the rads were clean as a whistle! And that had full bug screen and winter front inserts.