This has been beat to death I know.........but my horse is still kickin.
I ask other pilots what their thoughts are and half of them say don't do it, you are asking for trouble......detonation, vapor lock, deteriorating gaskets, the risk of ethanol, the list go on and on.
The other half (which uses it) say it is better for our low compression engines, no fouled plugs, no valve erosion, cheaper, and again the list goes on and on.
I burned 100ll in the 165 Franklin, leaned it aggressively.....stuck one valve and had problems with fouled plugs. TCP added to the 100ll seemed to end the lead problems, but it is nasty stuff and expensive.
I have 100+ hrs in the O470 with auto fuel and it seems happy. I add 2 or 3ozs of MMO per 10gal of gas, mostly because I think it will help my fuel bladders.
Last month I saved about $1.25 per gallon using auto fuel, doing the math at 13gph, in 1000hrs I will have saved $16250. If I make TBO the savings will buy my next motor.
I have yet to here anyone say auto fuel ruined my engine.
Does anyone on here have actual experience with using auto fuel and think it will lower the TBO on an engine?