I use the Mobil 1 synthetic 20/50 for V-Twins. As an aside I would also agree that changing the oil out religiously is probably more important than the oil itself.
I agree that that's the case for a water-cooled engine, but per JMD's above post, not for an air-cooled one.
I have been averaging 5,000 miles per year, so that does add up to one change over the summer, before the winter change.
I recall some 3 decades ago talking to the manager of a former standard oil refinery now making additives for oil (we were in rotary). Anyway they made and sold the additives which several other companies added to their brand of oil. In essence he said, "not all oil is the same"....
I would tend to agree with the above that not all oils are the same as is with gasoline too, but modern oils are made to withstand 15,000 miles + before oil changes. 5000 is certainly a very healthy average mileage but no where near the life of the oil even in a hot V Twin engine especially if you are changing it twice in a year. If helping to keep a hot V Twin air cooled engine cool is required then an oil cooler is going to be far more effective than the components of mineral v synthetic or additives. Having owned a Morgan for over 42 years (all be it a water cooled engine) I have never heard or read of any issues with any Morgans 3 or 4 wheeled where what oil has been used has caused engine failure or excessive wear and I bet in another 20 years I still won't have heard it for the current 3 wheeler, as long as a regular change regime is adhered too!!! Just like debating religion or politics there will be many different views but changing someone's direction highly unlikely, so we will probably all stick to what we believe is right, works for us and is within budget.
