Always lots of views on this but if you want long life between oil changes and the engine is (young) I recommend Millers nano fully synthetic 10-60 triple ester. A bit pricey but you won't be changing it for years....For older engines annual oil changing and use 20-50 classic oil (comma brand etc). BTW Millers is a UK product!!!
I was told (by a different oil company) that one of the reasons that nano is only used by Millers is that it creates a coating on everything inside the engine which is where the protection comes from. Repeated use over a few changes can cause that to build up such that oilways become restricted. I don't know how true this is but maybe has some validity. Otherwise I agree it is a great oil, I use it in my Fiat Coupe hillclimb car but may change to a different brand next time based on that information.