So often in the world we live in now it comes down to what helps you sleep at night. Old rules have changed in just about everything. It use to be thicker was better now not so fast more to it. Oil additives have changed, and they are all a lot better now.
M1 is a great product and so are a dozen others . Personally I think you will be fine. But 10 years ago I would have said change it, And I am sure I did say that then as did just about everyone.