I found that if I ran extremely rich, such as when I first got the plane, I would get a lot of plug fouling.
My instrument instructor then helped me with the math to show that running a reasonable ROP rather than extremely rich saved enough money to pay for an engine overhaul. Briefly, let’s say you burn 3 gal/hr more than necessary to run overrich to keep the engine cool. At roughly $4.50 to $5./gallon over a 2,000 hour engine life yeilded a cost of $27 to $30K which is about what the rebuild cost is for the TIO 540. His point was don’t burn the extra avgas when you save nothing on an engine rebuild. In short, if the manufacturer gives you a fuel burn rate of 16 gpm and you burn at 19 gpm under similar load conditions, you are wasting money.
Here are the assumptions; Lycombing recoomeds TBO at 2,000 hours, Continental is different at 1,700 hours. That the rebuild cost is a standard rebuild and doesn’t include excessive damage or turbo rebuild cost. That fuel stays at $4.5 to $5/gal over the 2,000 hours, that the 16 gpm provides you with the mfgr recommended chts and tits, etc.
Lastly: no mixture control on your plane???