There is no problem for the health of your engine operating very LOP. None. Do not let anyone tell you otherwise.
Paul and others are correct, it just results in much slower airspeeds, which is fine if you are trying to extract a long range out of a fuel load, the issue is the engine efficiency is not at its best, but it is more than offset by the greater loss of drag due to less airspeed. The optimum amount LOP is never a fixed number, it simply depends on where you are in terms of power.
John Deakin published this little table years ago on AvWeb, and what it does is gives you the recipes to aim for.
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Red Box = No Fly Zone
• At and below about 60% power, there is no red box. Put the mixture wherever you want it.
• At about 65% power or so, 100ºF ROP to Peak.
• At about 70%, 125ºF ROP to 25ºF LOP.
• At about 75%, 180ºF ROP to 40ºF LOP.
• At about 80%, 200ºF ROP to 60ºF LOP.
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Outside the Box
• At 65% power, use richer than 100 ROP, or leaner than peak EGT.
• At 70%, use richer than 125ºF ROP, or leaner than 25ºF LOP.
• At 75%, use richer than 180ºF ROP, or leaner than 40ºF LOP.
• At 80%, use richer than 200ºF ROP, or leaner than 60ºF LOP.
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Print that off and keep it in the plane. Remember not all EMS are equal when it comes to % power and if you start at say 75% power ROP by the time you are LOP you will be between 65-70% so you just take a rough stab at something like 10-20dF LOP on the richest cylinder and all is good with the world. Do not split % points. near enough is good enough.
My "go to" numbers for cruise are: 22.8 MAP, 2380 RPM, leaned to 7.5 GPH fuel burn, EGT's are usually low 1300's.
The engine runs smooth, no issues. With the Advanced LOP feature I did check it the other day. I am more in the 90-100 degree LOP range.
Since his comments I've been running 8.0 GPH. That's more in the 50-60 LOP range.
With all respect to my friends at Dynon and AFS, they lean find features are really a great teaching tool and for establishing the order of peaks, but in flight every day, they are almost useless. Hysteresis in probes, the speed at which you adjust, many things can confuse the algorithms so get comfortable doing it yourself.
I am not a fan of cook book recipes, your "Go To" numbers are fine but you have an RV, you want to go fast or go far. Pick which ever you need for the flight and do it.
Go Fast..... WOT, get every inch you can, use an RPM that is smooth, that could be 2364, 2348, 2507....I dont care, just pick a sweet spot. Then select the appropriate LOP setting, and the best way to do this is do a BMP (big mixture pull) and you will land square in the zone for appropriate LOP. If that is down low at 28.5" you will BMP it and land about 70-90dF LOP, but if you are up high at 22" it will be about 10-20dF LOP. It is almost like magic, but really you are surfing the curves.
Watch the video and play with the tool here >
http://www.advancedpilot.com/redbox.html
If you want to actually gain a really good understanding bookings are filling up for the Feb class in Brisbane, or March in Ada OK. It will be the best money spent in aviation.
Ohhh and the excess oxygen eating up your exhaust, you should be worried about that so please fly and store your plane in outer space, perhaps Paul D can suggest how to achieve that one, thats his backyard
Seriously, that is an OWT and has zero scientific credibility.
Just be diplomatic in telling your friend the earth is round not flat and he may be enlightened by you.
Hope that helps, but I seriously think investing in a class would be good for everyone. it is the only place you get to see what really happens inside your engine on the GAMI/TAT dyno.