I just got my first Omega, a pre-owned 2298.80. Is there any advantage/disadvantage to letting the chronometer run all the time, or will the watch hold up better and have more spring power reserve by keeping it locked at 12?
Your watch uses an Omega Cal. 1164, which is an Omega version of the ETA 7750. The watch is both a chronometer (meaning it has passed COSC timing tests) and a chronograph (meaning it has stop watch functions). You will get wide opinions on the question of leaving the chronograph running or not. My personal opinion is that if you want to leave it running, the impact will be pretty minor in the big scheme of things. There is a chance of increased wear on the chronograph runner, but that is not an expensive part to replace - maybe $25. Accuracy may suffer slightly, and although the power reserve will not change (that is a fixed value based on the mainspring length and gearing ratio) the amount of torque required to run the movement will be greater with the chronograph running. This means the point at which the torque coming from the mainspring is not sufficient to keep the watch running will come sooner than if the chronograph is switched off. Hope this helps. Cheers, Al