Two major things to be concerned with regarding GTDI engines in general, and one in regard to the 4cylinder EB engines in particular.
First, pretty much all GTDI engines will perhaps have potential issues with:
- fuel dilution... No engine oil can stop this, and really can't even mask the effects to any large degree. Once dilution affects wear rates, there's nothing an oil can do to stop it; not really even dissuade it. Generally I think oil selection in regard to dilution is grossly over-blown. We've seen plenty of data that shows low and moderate dilution doesn't seem to affect wear rates. And when dilution gets bad enough to affect wear, the oil can't knock the dilution off its evil path. So to a large degree, oil selection in regard to dilution is moot. People often look at a UOA and stare at the fuel %, and then make a decision; that's not the right method to make a judgement. Rather, people should look at the wear rates; if they go unaffected, the fuel % is moot. If the wear rates are affected, then it's become a problem. It is literally that simple. The oil you choose isn't going to greatly affect this one way or another.
- intake valve fouling,,, Here, a high quality oil with a very low NOACK score (or pragmatic equivalent) will help reduce vapors leaving the crankcase which are bound for reintroduction to the intake tract. I do believe that using a high-quality oil in this regard may have some positive residual effects (pardon the pun). This is one area where oil selection can make a significant difference. There are a few products which have very good NOACK scores; some of the Mobil1 and Pennzoil products for example (some, but not all). But, I believe that the brand of oil most likely to reduce this concern to a very low level of risk is HPL; their lubes are nearly off the chart (in a desirable way) in controlling evaporative vapors because of the base stocks, additive selection, etc. I have decided to run HPL lubes in my two GDI engines because of this concern. Some OEMs have gone to a dual-fuel-injection scheme; this helps. But again, that's a mechanical solution to the problem, not an oil related one.
- 4cyl EB engines themselves... They have a design where the cylinders were not fully siamesed and the head gasket surface area between cylinders is VERY thin; so much so that this has caused problems with eventual gasket seal failures in many engines. Ford did improve the design a few years back, slightly, by altering the design to provide coolant cross-flow via a drilled path rather than a sliced cut. But, NO ENGINE OIL is going to solve this problem, so it's a moot point in regard to your question.
That's my non-expert take, anyway.
www.pennzoil.com
