Big Jim was nice enough to PM this to me:
"I really like Mobil 7500 (synthetic blend), but if uncovering oil leaks is one of your primay concerns, a high mileage oil would serve you better, such as Valvoline MaxLife (dino). If the engine is sound and you are overly concerned about potential leaks, Mobil 7500 would be a better choice."
Up in my area, oil is expensive, and there are never sales.
Mobil 7500 = $3.50/qt.
Valvoline MaxLife = $3.50/qt.
Mobil 1 = $6/qt.