Hello again I don't get on here much to post but I read all time. One thing I know is there isn't another group of people who know more about oils, and I mean that as a compliment. On another point, I have another oil question I would like to throw out for opinions. Still driving a 2003 gmc envoy. Currently has about 145000 on the odometer. I drive probably 90% or more highway miles. Put over 20000 miles on her in a little under a year. I use fram ultra oil filters exclusively just because I believe in them. I just changed out one that I ran for 2 oci's for about a total of 12000 miles. The " change oil" light came on about the last 1500 miles of the last fill of 5 quarts castrol gtx ultraclean 5w30 and 1.5 quarts of castrol gtx magnatec 5w30. Engine sounded smooth on this combo, though I know sound isn't everything. Current fill is 7 quarts castrol gtx magnatec 5w30 and a new fram xg3675. I'm considering running this out to around 8k for the oil before changing but using the filter for 2 oci's again. Everything I have read on here tells me the filter is up to the task. I'm only wondering if the oil is up to that oci? I am of course considering the 7 quart sump that I'm assuming makes it fairly easy on oil. Anyone else ran the full syn gtx magnatec that long with decent results?