Just wondering ... My first trip with GC in the crankcase produced a 2.7 mpg drop from 29.7 mpg to 27 mpg. Car is a 2005 Subaru Outback 2.5i. The last oil fill was Mobil 1 EP 5W-30 with LC20 and VSOT. The GC is straight out of the bottle. So I wonder if it needs some break in, since the additives changed? Or, do I need to add the LC20 and VSOT to get the same benefits I had with the last fill? I remember that I thought that the LC20 and VSOT helped the M1 5W-30 get the 29.7 mpg to 32 mpg. I didn't want to mess with the GC additive pack...but a 2 mpg + loss is real money.