Im currently using GC in my truck, would it hurt to switch to NEO 10W30 in the summer and then switch back to GC in the winter? Since GC appears to have mainly esters, I was thinking of trying NEO's 10W30 which is diester just to keep the oil in the same category. I have enough GC in my garage for 3 more changes, but wanted to switch in the summer because it gets so hot here (NC) and there is no GC 10w30. I plan on getting a quart of NEO to send in a VOA to see what you all think of it since no one has done that with that brand yet. It seems that people switch oils all the time on here, I was just wondering if in the long run there would be any problems.