I think the key is switching to synthetic AFTER it is broken in. For the cost of conventional 15/40, I still feel more comfortable changing oil yearly to remove acids. You never know when you may need to run it for 200+ hrs in an emergency and I want it to be ready. Every diesel I own calls for minimum 1 year oil changes.
People will "polish" fuel which can keep for years but not change oil, and that seems kind of crazy to me.
People will "polish" fuel which can keep for years but not change oil, and that seems kind of crazy to me.