is 87 octane safe for C280?
 

Just wanted to know if I HAD to spend more for fuel than necessary...I live in Maryland and it's freezing now...My plane loves the cold :-)

Short answer is stick with premium.

I think with a 10:1 compression ratio, and a DOHC head, that 87 will result in the the engine retarding the timing to prevent detonation, which in turn will prevent damage to the engine but will result in a loss of fuel economy due to the fact that less energy will be harnessed from the fuel becuase the later timing will result in a loss of efficiency. So, you may be able to get away with 87 without engine damage, but MPG will drop as a result with no net savings in the end.

Nice signature. Unlike an aircraft piston engine, which is purely mechanical in nature, the M104 can detect detonation and prevent it but sacrifice efficiency in the process. Your standard lycoming or continental will just get blown apart if its bad enough. Funny how a an engine with no higher than a 8.5:1 compression ratio and single overhead valve needs 100 octane fuel to run. Most of the older engines that can get STCs for 87 octane car gas have compression ratios lower than 7:1.

My J-3 can run auto gas and I do use that most of the time...It only runs about 4-5gph for 2hrs at the most(need to pee by then) and I have no problems...

I have to change a common saying of mine, it used to be, how do you get a small fortune in aviation?...Start with a large one...New saying: how do you get a small fortune in aviation and Mercedes ownership?..................lol

Off topic but...
 

a wise old pilot once told me -- the way to make money selling rides in an airplane...

...give the passenger a dollar and tell them to go away :P