I agree regarding running 100LL for the first 50 hours or so. In fact, the new ECI cylinders on my 0200 recommended (maybe required) 100LL for the first 50 hours. The lead helps build a 'cushion' between the valve and the seat and promotes better seating in my humble opinion. At near 100 hours I still run a pretty heavy mix of 100LL and auto fuel but am gradually 'weaning' it off and on to 91 octane auto with an occasional drink of 100LL.
I have a Jacobs radial and run a lot of Auto with no MMO. If I can't get auto on a trip, etc. I will run MMO, but only at the published ratio of 4oz for every 10 gallons. More is not better with that stuff and I don't think the plane runs well with auto gas mixed with MMO. I run it in the oil as well. First annual I had a dead #5 cyl and after running auto for a year I'm fine, no more lead issues. The low compression engines don't like lead, and the 100LL these days has a lot more lead than 50 years ago. A mixture of 75% auto and 25% 100LL will produce the same lead content as when my plane was new in 1947! No wonder we have so many valve issues!
I've been using ALCOR TCP with 100LL exclusively for years now. My engine has a Stromberg NAS-3 carb with no mixture control installed. I found that if I didn't use TCP the plugs would quickly develop lead deposits and one of the lower spark plugs would foul, which I'd only find out about during the run-up. With TCP, there's no plug fouling at all.
I've never used auto gas except to try it initially, when I found that it sooted excessively causing plug fouling. Now, ethanol free car gas is unobtainable locally and I don't dare burn gas that contains it because it'll eat the zinc carb body.
If you're not using 100LL there's no reason to be using TCP as all it does is prevent lead deposits.
Here's where somebody chimes in to say that they've been burning car gas with ethanol in it for 15,000 hours with no ill effects.
I have never used TCP never seemed to need it in my J3 Cub with a C-90 engine. I think TCP may have been aimed more at Cessna 150s which had a problem fouling plugs in flight school use. Haven't had that problem with my plane, not sure I ahve ever had a plug foul.
When I bought it about 1985 it had approval for auto gas so I tried it a couple of times, using AMCO lead free. It ran fine, I didn't see any difference from av gas.
A Cub burns so little fuel, less than 5 gal per hour, that I didn't see much point in going to the extra trouble to save a few bucks per day, and 100 ll av gas is more convenient since virtually all airports have it.
So I have used 100 ll since and never has a problem, it seems to run the same. My engine starts first pull most times when cold and usually first or second pull when warm and idles well.
I have a Stromberg carb with a fixed mixture control with no mixture control cable. I does, I think have an arm on the carb that is wired in a fixed position and a little leaner than full rich since I live at 7800 feet and fly mostly from 5000 to 12000 feet.
MMO doesn't do anything for lead. It's a light solvent oil which may help in getting rid of some of the lead accumulation (particularly valves) but it's not clear it's helping with the overall health of the engine. MMO doesn't "publish" a ratio for any aviation use, just auto and marine.
Of course, it does make your engine minty fresh.
Check out www dot pure-gas dot org to find locally available mogas that hasn't been adulterated by the scam the oil companies used to dupe the dopes we elected and sent to represent us in DC. I run booze-free mogas in my Franklin 90 with MMO at 4oz:10gal ratio, just like I used to in Stearmans with 220 Continentals and R680 Lycomings up front. I never had top end problems unless some dope flew off somewhere and ignorantly tanked up on the blue stuff.
As an A&P/IA, I agree that running 100LL, thinned out 4:1 with mogas, during the initial break-in period after a TOH or MOH can coat the valve stems and keep them slippery. But once they're coated, like after one or two tankfuls, avoid the blue fuel. Remember, when you take your old dog to the vet to be put to sleep, they get an overdose of blue stuff that looks a lot like 100LL. Perhaps too much 100LL is to old, low compression engines what too much sodium phenobarbital is to old dogs.
Not the oil companies but the corn lobby.
It takes 1.18 BTU's of energy to make the quantity of ethanol that will produce 1 BTU of energy. That extra .18 BTU is produced by this funny stuff that comes out of the ground...I believe it's called oil. Monsanto and the oil industry have been bed fellows in DC for a long time. But enough about those miserable, greedy bastards, let's go flying!
MMO doesn't replace lead for lubrication but you might still want to consider it. After rebuilding the fuel valve in my Cessna 140 several times (brass on brass, typical galling) , an unidentified A&P suggested adding some MMO. That was 3- 4 years and approximately 200 hours ago and I haven't had to rebuild my valve since.