I haven't raised any concerns about it on any forum but I'll confess, I've been a bit concerned with the all-aluminum engine. Not only bad experience with an early '70's vehicle with aluminum heads but a dozen years as a machinist and now twenty-five years as a mechanical designer cause me to worry a bit. Cast iron sleeves in an aluminum block don't ease my worries any. If you understand the difference in the thermal expansion rate of aluminum vs. cast iron, you know why. But after a little research, I feel better. Here are a couple of excerpts for those who don't want to dig too deep and a link for those who might. http://www.flame-spray.com/ "An important goal for engine manufacturers is to reduce fuel consumption, which can be accomplished by decreasing overall vehicle weight and improving engine efficiency by reducing the internal friction losses. Substantial weight savings can be achieved with the use of aluminum engines. However, most aluminum engines require cast iron liners to be used as the wear surface. Additional weight savings and potential friction reduction can be achieved by replacing these heavy cast iron liners with a low friction, wear resistant PTWA coating on the cylinder bores. Additional benefits of PTWA in new production engines include improved heat transfer and decreased bore distortion, which reduces friction loss and oil consumption." "Flame Spray Inc., Port Washington, N.Y.,announces that the Plasma Transferred Wire Arc coating process has been selected by Ford Motor Co. to coat the internal surface of the aluminum engine block cylinder bores in the Ford Shelby GT500 sports car. PTWA provides a lower cost and lower weight alternative to cast iron liners, while delivering increased displacement in the same size engine package, and a potential for better heat transfer."