SAKGuy,
Since all Opinels change day to day in terms of their tightness, I think in terms of "average" tightness. I control the "average" tightness in 2 ways. First, I carry and use it for a bit. Second, I control the basic tightness by adjusting the inner collar.
Remove the outer lock ring. To loosen, use a large (very large) standard screwdriver and carefully twist in the slot to open the collar just a bit. I do this with the blade open and closed and open the collar on each end of the slot. Take care not to damage the wood. To tighten, use large pliers and crimp the inner collar closed a bit.
IME, Vaseline and Mineral Oil (both good) are more about making the joint less susceptible to getting tight when wet or in humid conditions.
WMB, as a recovering carbon steel snob, I wouldn't hesitate getting the steak knives in stainless. The Sandvik 12C27 sharpens well, holds an edge longer (its a bit harder) and doesn't transfer taste to food.