Originally Posted By: Shannow
I wonder why Honda would specify "obsolete" 10W-30 for the engine, when the 20 weights that they specify in the roadgoing engines offer clearly superior performance and protection...(well according to the advocates of said engine oil).
It's all about the add pack. The older oils have add packs that are beneficial to highly loaded marine engines, but not emission systems. The newer oils are beneficial to emission systems but not as beneficial to highly loaded marine engines. There is nothing wrong with the slightly older oil formulations as far as engines go, they just are not friendly to modern emission systems in autos.