Pennzoil & QS High Mileage

[Gene K]

According to Noria Pennzoil HM and Quaker State HM 10W-30 are a blend of all 5 Groups as of 2018. I'm assuming the GI is the carrier oil and used for solvency and that GIII / GIII+ (If used), GIV and GV are in small amounts but still that's odd for an oil labeled as conventional.