[CZappettini]

ive had my 65 mustang for a while now, and ive been using premium, because thats what my dad used when it was his, and so thats what im using. my question is, is this necessary?

[venom800tt]

I dont think premium is necessary for carburated engines, i had couple 70s cars and never put premium, in fact i think old cars like regular 87 gas better, my friend has 70 and 71 Mustang and he always uses regular, but still i never owned one personally, so still don't count on my words

[Warrior 2011]

i put premium gas in my '68 with the 289. To me it just seems to run better on the higher octane gas.

[andrewmp6]

Unless you got some built up mean engine 87 octane is enough for most older cars.

[kawik99]

i know someone has two chevelles( i know not a ford) but they are a 68 396 ss and a 71 ss. he puts cam2 in both cars but a 50/50 mix in the 71 woth cam2 and premium and 25/75 in the 68. cam2 is a racing fuel and can be pick up at some gas station here but the caatch is it cant be pumped into the car. it contains lead, big fine for the station if they do. insted he puts it in a jug and puts it in his car when he gets home. id say it helps alot in the preformance, but not sure on the affects. also werent thos power plants built during leaded gas?

[andrewmp6]

The lead was to help the valve seals if its never been rebuild your find there is still lead stuck on the valve seals.i had a 65 impala ss the 396 i used unleaded 87 on it for 4 years of daily driving never hurt it.

[Warrior 2011]

yeah all of these early engines were made during the days of leaded gas. i also have an owners manual for my 1968 mustang and it says that 289s should use at least 91 or 93 octane fuel. I cant remember which one of the top of my head rite now.

[RedGTvert]

Originally Posted by venom800tt

I dont think premium is necessary for carburated engines, i had couple 70s cars and never put premium, in fact i think old cars like regular 87 gas better, my friend has 70 and 71 Mustang and he always uses regular, but still i never owned one personally, so still don't count on my words

Has nothing to due with a carburetor, it has to do with compression. Try running regular with a high compression engine.

[Jay H 237]

I use 93 in my stock 289 68. It doesn't like the lower grades but that could be the way the carb and timing is set too. I dump a bottle of lead substitute in it every other tank or so.


In theory you should be able to use the lowest grade without the engine pinging. If the engine pings with 87 but not with 89 then you know you can run 89 or 91(3) in the car without problems.