As Bob mentioned, the cost savings seems silly. Reading some information here and the SHO forums, I decided to make the switch to premium. When we first got our EB Flex we ran regular up until about 2,500 miles. You have convinced me,I will be happy to spend the extra $2 Also at high altitudes it can be hard to find anything more than 91 octane. I run 93 from BP almost exclusively when at home but on a long recent trip I had to settle for lesser fuel. I run only premium (91 octane or better). Taz wrote:I just thought IвЂ™d add in objective info rather than subjective info. The EB might tolerate it but why not advantage of what the motor has to offer? My logic is as others, why risk such an expensive motor by using cheap fuel? By the non-EB motor if you want to go cheap. Too much risk as detonation can destroy a motor in half a second or less if it I bad enough. I prefer to have a little bit of a margin and not be on the ragged edge. For maximum performance (economy and HP) typically you want the maximum amount of timing advance you can have just up to the point before detonation (pinging) starts. Retarding timing too much is typically bad for exhaust valves and turbos as it can cause EGTs to go way up. I know make sure that no matter what I run at least 91 octane or better. All it took was my loaded Flex, hot day (95F +) steep hill and 90 octane or worse fuel. I doubt most people would experience this but it is entirely possible and was repeatable. The ECU could not pull timing both quick enough as well as enough degrees to prevent the pinging. I had some less than ideal fuel and had issues with pinging under load. Put in crappy fuel and the ECU will start to pull timing to reduce detonation. I have found that I can have significantly more advance when running better fuel. This gives both better fuel economy AND performance. Higher octane fuels can have more timing advance without detonation. Timing advance tells you a lot about the fuel you are running.

I use a ScanGauge II in my car that allows me to monitor a lot of different parameters.

I just thought IвЂ™d add in objective info rather than subjective info.

Ford flex type of gas