Tony,
Perhaps your question i
Tony,
Perhaps your question is the most difficult and controversal question ever posted on F-talk...as there is just so much hype, and self-proclaimed experts on this subject, as you have found.
When all else fails, let's look at what the factory recomends, and go from there...Also, what are the minimum ambient temperatures where the vehicle is located...
From your list, I use 15-50 Mobil One in my BB, year-round...though the car is only started and driven in the warmer months.
Extreme cold conditions might dictate a "thinner" oil, as most of the engine wear occurs during start-up. On the other hand, I totally disagree with running a 5-30, or 10-30 oil in a high-reving engine...as some have proclaimed to be "OK".
I do agree with the statements that thinner oils flow better, hence lower oil temperatures. Hoever, I feel that "thicker" oil provide better lubrication qualities (shear protection) at higher revs, and resulting engine temperatures.
So...a balance is in order to protect for all conditions...
Regardless of what oil is ultimately used, frequent changes are still the best protection against engine wear!
Regards,
David