stang23456

I have an 04 GT and have heard what it seems to be a slight knocking out of my vavles when I get on it in 5th gear. Will it be ok to run 89 octane in it ? I have heard we should only run with 87 !!

POISND U

If you're hearing knocking on an 04 then something's probably wrong, but higher octane won't hurt an engine.

Jon S

I run 87 with no problems, but it couldn't hurt to try some 89 or 93. wait until you're near empty and put 5 - 6 gallons in and see how it is. If it still knocks, it may be a bad sensor.

Quicktime_GT

there is probably nothing wrong with your car. Usually if you valves are chattering, which is a good sign of pre detonation, you'll hear it right after you first give it gas at idle. Like if your car is idleing an you just stomp it.. is what i'm trying to say.

Frostbitten

use 93!

03 GT

I run 89

ripper

If i ran 89 and stomped it id be puttin a new headgasket on. [sm=bustedsign.gif] For a stock motor 89 should be fine. Detonation is a killer watch out bud. Dont go whompin on it till you figure out what it is. You might just have a bad tank of gas.

Dan04COBRA

Did you buy the car new or used?

If you bought it used, it might have a 'performance' tune in it that requires higher octane than 87.

Are you sure you are hearing engine noise & your not just lugging the engine in 5th?

M1ke

i think i know the sound you're talking about and its not knocking. you're just trying to accelerate in 5th = not gonna happen That is unless you're going like 100mph
its just the engine bogging down. i hate that sound. just downshift to 4ht

04BlueGT

That's what I'm thinking. I run 89, but I have the timing advanced to +14 (+4 over stock). Before the timing advance, I ran 87 all day long.