FYI for those claiming Top Tier fuel or additives have any effect. your engine is direct fuel injection. No fuel touches any internal part so nothing is "kept clean" by doing so. Watch this video (yes, a Ford, but excellent explanation of port injection where top tier fuel had a definite benefit) as there are illustrations and more so all can understand there engines hare very little in relation to the old port injection engines. And so much misinformation is spread via dealer, etc.
Just sharing to help owners understand their engines and the special care these need. ONLY use a full synthetic oil. The 5w20 is ONLY to allow the automaker to meet Cafe fuel standards. You want a 10w30 for normal driving and consider like Amsoils 5w50 for hard driving.
91-93 Octane and your engine will run more efficiently as the 11.5:1 CR is capable of using even higher octane. It does no harm to use 87, just power and fuel economy is lower due to timing retard.
Any in tank additive is pretty much throwing away $ as is any top tier fuel. Only use a fuel injector cleaner at most every 20-25k miles. These injectors operate at 2000-3000 PSI.
NEVER use a solvent based engine running upper induction cleaner such as Seafoam or BG, etc. if over 15k miles. They do little to remove the coking deposits but what is loosened is a very hard abrasive nature and smaller particles get forced between the piston and cylinder wall causing scouring.
GDI engine experience many times the raw fuel washdown as the old port injection engines so your motor oil is under severe stress from this and the other contaminants that enter the crankcase. So a proper truly effective air/oil (catchcan) crankcase evacuation system will remove most of these before they can mix with the engine oil. If not, changing oil at shorter intervals is a good idea.
Hope this helps clarify as so much misinformation is spread out there.
Elite Engineering USA
Your GDI Specialist