08-23-2010, 03:09 PM
Anyone remember what the factory recommended fuel grades for your Mach were in the 70s. In California, current octanes are 87, 89, and 91, which is considered premium. 
08-23-2010, 04:03 PM
According to my 1972 Owners Manual it says exactly.
All 1972 engines are designed to operate on "regular" gasolines with an octane rating of at least 91* when engine is adjusted to factory recommended specifications.
To obtain best performance with these fuels, it is important to have the maintenance services performed at the recommended intervals.
If you plan to drive your car outside the United States or Canada, check into the quality of gasoline available in the area you expect to visit.
* Octane as rated by the Research Method
All 1972 engines are designed to operate on "regular" gasolines with an octane rating of at least 91* when engine is adjusted to factory recommended specifications.
To obtain best performance with these fuels, it is important to have the maintenance services performed at the recommended intervals.
If you plan to drive your car outside the United States or Canada, check into the quality of gasoline available in the area you expect to visit.
* Octane as rated by the Research Method
08-24-2010, 10:27 AM
-that info is appreciated! Think I'll try to use premium more often then. Can of octane booster may be too expensive ...
example,
for 10 gallons of gas:
premium is $32.30
regular is $30.30
octane booster is $4.00 to treat 10 gallons of regular
example,
for 10 gallons of gas:
premium is $32.30
regular is $30.30
octane booster is $4.00 to treat 10 gallons of regular
08-25-2010, 02:46 AM
I find my 351 Cleveland runs best on Texaco/Shell super unleaded. I do not add any octane boosters, since Ive read they eat the seals in your carburetor. A lot of guys in my Mustang Club refuse to use octane boosters because of this reason.
08-25-2010, 11:00 AM
On a similar subject, I bought the LEAD additive since my valve seats have never been re-seated for use with un-leaded fuel. But I have not added it to the tank for the last few fill-ups.