Particularly as it relates to the oil pressure operated valve timing gear? I did the entire "what do I do now!!" routine back in the early-2000's when Ford first started specing 5w-20 and I couldn't even find the stuff for the 4.6L motors, at the time I just gave up and used 5w-30. But the newest family acquisition is a 2014 Mustang with the aluminum 3.7L and mucho valve timing valve train. Being a new motor design, and knowing it would be specced for 5w-20, and using the oil to set timing, can the more mechanically inclined tell me if the difference between 7 cSt or 9.5 cSt at 100C makes any difference whatsoever to such a valve timing system? Just based on the decreased viscosity at lower temperatures during startup and warmup it would seem logical that the valve gear would need to handle much lower viscosity oil without grenading during these time periods. But I thought I would check just in case.