We often hear that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate. This a motto of some oil companies advertising synthetic oils. My literature review clearly confirms the concept of startup wear. That has been documented by numerous scientists and seems to correlate with low oil and coolant temp. Some evidence points to chemical nature of such wear. It is also clear that low viscosity and/or synthetic lubricants can increase fuel efficiency (by modest amounts, 2% across the board) while not increasing wear by a significant measure (speaking pragmatically, not statistically). Now, did anyone come across an empiric and scientific study showing decreased start up wear with either synthetic or lower viscosity lubricant? Is this a fact or just a myth? Please, no "feels like it should" or "has to" statements.