For GDI engines - the best base stocks with the lowest amount of viscosity improvers and NOACK are key to prevent intake valve deposits . Valvoline Advanced and M1 are very good in those respects , Quaker State Full Synthetic is the best in the value price category , Pennzoil Platinum is in the middle and Castrol is surprisingly poor . If I were to keep a GDI vehicle long term I would be concerned with the oil I chose as well as the OCI I decided to run .
10W30 QS FS for low VM treat rate - and just a nice oil overall. But now you ain't in Georgia!
I frequently short trip (8 to 12 mi one-way) and I change the oil Spring and Late Fall. That works out to be only about a 2500 mile OCI.
The oil looks like well used kerosene parts washer fluid when it comes out. Colourful bubbles. Sooty and thin.
I have Valvoline advanced 5W30 in there now. It was on sale where QS was not. it had been a good oil. Not happy with full warmed engine noise with this batch. Runs like a 5W20 compared to the QS FS.
But, the engine may be
done for after seeing some severe fuel dilution a few OCI ago. Sounds like rod bearing rap when you lift off the throttle.
Oh well, I have two more years of engine warranty.
p.s: From where did you get the "info' on VM and NOAK and who stated they are "key" to prevent intake deposits?
Oil is whipped into a mist and fog in the crankcase - it's going into the PCV and the intake regardless, IMHO.
Some may propose a Baffled Catch Can? I dislike adding "junk appendages" like that to a modern engine. Any such contraptions would have to be quickly dispatched if the engine went
kablooey.
- Ken - in his drafty old log cabin on a hill