tropclbane

Would appreciate any helpful advice regarding type of fuel to be used for a classic mustang.
Could unleaded fuel possibly damage the valve seals?
Should i be using any additives (Led) every time i fill up?
Thanks much for any help

Bane

Deviousfred

Regular Unleaded

lunarweasel

.... WITH a lead additive.

1slow67

What does lead additive even do? I have never used it and my dad told me I didn't have to since the engine was rebuilt.

jonward786

not necessary

THUMPIN455

Unless you are pulling a trailer with your Mustang, or driving constantly up large steep grades, you most likely wont have any issues with the valves. Tetra ethyl lead is illegal, highly so in California since state as well as Federal laws severely prohibit its use. Its main use was an octane booster since the group of hydrocarbons we normally call gasoline has an octane around 65 to 67 on its own.

If you happen to have high compression, as in over 10.5:1 with iron heads, you could benefit from running E85 if its available in your area. Also some people will say otherwise, but even 10% ethanol in your fuel will help with pre-ignition problems on higher compression engines. Before anyone says it is bad for your car, know that I have run nothing but 10% in two engines from the 60s, and I bet they worked much harder than your 65's engine will. I have not experienced any issues with corrosion or any other supposed detrimental effect on any of my vehicles from running ethanol.

That being said, you dont need to run anything special unless you have a K code with the solid lifter 271 horse 289 that had higher compression than the regular 289s. If its a six it will run on pretty much any fuel you put in it, other than diesel of course. If it is a K code, you should look into E85, the power increase alone is often worth the switch to a 105 octane race fuel you can get at the pump, often for less than the cost of 87 octane.

Yeah I like the alky, and I dont care where it comes from. It makes lost more power and leaves a nice clean engine that never overheats. I run it in my cars all the time.

mstngsule68

you need to have new valve seats in it if its been ran on leaded gas if your puttin in unleaded, or have a lead additive, plus its a good way to break it to the wife that u need a valve job done or some better heads lol

mstngsule68

cuz it will burn up valve seats....

htwheelz67

2v 289 87-89 octane 4v 289 91-92 octane but you will have to back off timing a bit.