Hi all, Why is it that many auto manufacturers do not require synthetic oil for thier Turbo vehicles? Ford EcoBoost 3.5L V6 EcoBoostTM engine Use SAE 5W-30 engine oil Only use oils “Certified For Gasoline Engines” by the American Petroleum Institute (API). An oil with this trademark symbol conforms to the current engine and emission system protection standards and fuel economy requirements of the International Lubricant Standardization and Approval Committee (ILSAC), comprised of U.S. and Japanese automobile manufacturers. To protect your engine and engine’s warranty, use Motorcraft SAE 5W-30 or an equivalent SAE 5W-30 oil meeting Ford specification WSS-M2C929-A. Refer to Maintenance product specifications and capacities later in this section for more information. 2010 Mitubishi Ralliart and some say, even the Evo No manual information found but this was my last car and it never specified Syn either Hyundai Santa Fe Sport 2.0T For better fuel economy, it is recommended to use the engine oil of a viscosity grade SAE 5W-30 (API SM / ILSAC GF-4). However, if the engine oil is not available in your country, select the proper engine oil using the engine oil viscosity chart. (10w30 or 5w30) To name a few... Are conventionals that good now-a-days? I do know that the SN rating points out 'for turbo protection' but are the formulations/additives that good to protect for 3-5k miles? Thier engineers seem to think so i guess.