My interest in DI engine maintenance has peaked now that I recently acquired a new 2013 Ford Focus ST!
We all know the pros and cons of DI engines. It certainly sounds like a low sulfated ash, phosphorus, and sulfur (SAPS) motor oil is the way to go. Problem is, there aren't a whole lot of them in North America. We know that Pennzoil Ultra is one of them (that I know of off hand) that carries the VW 504/507 spec for low SAPS.
But are deposits in the intake valve seat and stem really really a concern, especially for a Ford vehicle? The reason I say this is that it seems Ford is at least ahead of the curve when it comes to addressing this issue.
"Stephen Russ, technical leader for combustion for Ford’s 2-liter Duratec DI engine, said that similar to GM, engineers have determined the proper injection-timing calibration to help eliminate the carbon deposits. But Russ also said the technology of injection components – particularly the high-pressure solenoid injectors – has quickly matured, meaning excess valve deposits in most DI engines should become a thing of the past as these improved components are incorporated into production." http://www.edmunds.com/autoobserver-archive/2011/06/direct-injection-fouls-some-early-adopters.html
Not only that, but check out this patent by Ford:http://www.google.com/patents/US6178944
"A control method and system is described for a spark ignited, four-stroke engine having multiple combustion chambers, each coupled to at least one intake and one exhaust valve, a fuel injection system for injecting fuel directly into each combustion chamber, and an electronically controlled throttle for throttling air inducted through an intake manifold into the combustion chambers. Comprising:
1) Detecting when to initiate an intake valve cleaning;
2) Indicating when the engine is operating in a homogeneous mode wherein the throttle is partially closed and fuel is injected during an engine intake stroke to generate a homogeneous air/fuel mixture; and
3) in response to said valve cleaning detection and said homogeneous mode indication, injecting additional fuel during a valve overlap of the intake and exhaust valves so that fuel is drawn into the intake manifold and subsequently inducted back into the combustion chamber past the intake valve.
Really really cool stuff. So it does look like Ford thought about these deposit issues wayyyyy before our time. Does make me rest easier on the EcoBoost 2.0T design and execution. Don't think it hurts though to stick with a low SAPS motor oil if you want to do your own changes, or MotorCraft.