I realize that oil consumption may vary quite a bit, but I want to get an idea of what the acceptable range is and when (absent any other signs of a problem) I should start to care? Lycoming O-540-B4-B5, currently I usually add a quart maybe every 4 or 5 hours of flight time, give or take. Seems a little high, but no other signs of issues; compressions all in the mid-70s. Last oil analysis showed just slightly high iron but otherwise nothing noteworthy; next one coming shortly. Thoughts? Thanks!