Engine builders and doctors like the rest of us are human beings and the thing that Hitler learned from Lennon is that a lie told often enough becomes the truth and we are all susceptible to that. Engine builders believe the same wives tales that most all of us do. Thick oils do not protect engine parts better than thin oils. Film strength is what does that and the higher that it is the more protection you have. They do allow the oil pressure to stay higher at hot idle but again if your oil pressure comes below something that you're comfortable with that's when you need a high volume oil pump. There's another thing that most all thicker oils tend to have in common and do better generally speaking than thinner oils and that is that they tend to have a typically much higher temperature at which the onset of thermal breakdown starts to occur. There is also a third thing that I can think of that thick oils consistently do better than thin oils and that is that when you run a thicker oil, the engine will burn less oil. Oil pressure, thermal breakdown, and oil consumption are the only three things that improve when you use thicker oils and they improve just about every time. Film strength is not improved by higher viscosity nor is it improved by zddp and the common myth is that both of those things improve film strength but it's just not true. Again, that's not to say that you can't get a thick oil that has high film strength but you can't attribute its film strength to the viscosity, it's attributed to the additive package. There's no reason why thicker oils couldn't be some of the most protective oils but in real life when you measure their film strength most all of them fall short except for one, amsoil 10w50 dirt motorcycle oil which has a film strength of 134,968 PSI and is the number six oil in 540 rats oil film strength list. The number 11 highest strength oil is Quaker State full synthetic 5W30 with a PSI reading of $133,302. The next highest 50 weight motor oil on the list comes in at number 35 and it's amsoil signature series synthetic 5w50 with a PSI strength of 118,543. In the 249th position on his list is mobile one synthetic 15w50. I don't know if this is the same one that you use but it has a film strength of 70,235 PSI and that's not good. And of course the 10w50 amsoil dirt motorcycle oil is 18 or 19 dollars a quart. It will do all the things that a thick oil does for you currently but it also has incredible film strength.