So first post, but 15 year learner on this amazing site. I have learned more than I ever dreamed from folks here. I found this thread so interesting I finally joined. I like all of the atmospheric density science going into this. Like seeing the same science used to illustrate a car does not vacuum or draw in air to the cylinder, but rather the ambient air is pressed in to the negative pressure space in the cylinder. So we up here at higher elevations suffer for power. Our diesels exhaust more black unburned fuel and make less overall boost pressure. Run hotter EGT's and such. I would like to present the theory that Ford in this instance has placed the altitude along with a lower 0w rating most probably due to the turbos and their oiling requirements at altitude.
When the vehicle is started, it takes time for the oil to reach the turbo bearings. At lower elevations, the turbine shaft will spin at a given velocity at any load. At higher altitudes, the turbine shaft will spin higher for any given load, due to less air density resisting the pressurization. So if at lower elevations we demand 10lbs of boost the turbine will spin at 80k rpms as just an example number. At 9k feet, to achieve the same 10lbs of boost, the turbine shaft will spin faster to make the same boost numbers, perhaps 88k rpms or higher. If we start an EcoBoost at higher elevations and begin to place a load, the turbine spins up quicker. It is my guess that due to this increased rpm for any load, the turbo will need oil volume faster than lower elevation rpms demand. Oil whip could be a concern at the bearings if the oil is too thick? So not being a smart stinker at all, just proposing a new theory for the topic is all. Opinions on the 2 cents?
