Quaker State Full Synthetic,
My thinking is that Quaker State is a suitable replacement for ACDelco, it is easier to get hold of (Walmart) and costs about 1/2 as much. Thoughts?
1. Which Quaker State Full Synthetic 5W30? Just QSFS, or QSUPFS?
2. Either QSFS or QSUPFS - singly or in combination with the others - 5W30 should be a suitable replacement.
In fact I would not hesitate to use QSEFS in combination with either or both of the others. All QSFS are excellent, even QS High Mileage FS.
Other Group4 Full Synthetics I'd not hesitate to use at oil changes:
Pennzoil made from natural gas (both Quaker State & Pennzoil are owned by Shell, but made in different factories, differently)
Valvoline (I'm in the middle of trying 'Restore & Protect' for the next 4 oil changes)
Mobil1
Amsoil Signature Series
Other full synthetics are 'questionable'; will only use them BETWEEN oil changes IFF I'm experiencing oil consumption as topoffs -
which I do not consistently experience because my driving is inconsistent.