CoyoteDriver

I read that putting 87 decreases 18 Hp in a 13 gt, is that true? I out 87 and don't feel a difference. I have put 91 a few times but decided to stick to 87

audioAl

In a 5.0 I'd burn 91-93 octane only. Variable cam timing is involved, research it.

05 Mustang

welcome

until I boost it, I'm just going to meet in the middle with running 89.

AJ06GT

After having a long discussion about this the other day, the Coyote engines are advertised at full power (420 HP) with premium only, otherwise they do lose a little power. The power difference will likely not be noticeable at all though, so it's really up to you. You're not hurting anything by using 87, other than missing out on those extra few ponies.

96t-bird

Welcome.

johnny_raincloud

91 Octane ONLY!

Then again, its also preference and due to the fact that my tunes are written for 91.

Stang BB

I don't use mine as an everyday driver so I run 91.

Derf00

I believe the manual say Premium fuel recommended? If that's the wording then use what you want. If it says required that's another story.

90nSSMD

I run 93. My base timing is advanced to 14*. Don't want engine pinging, so gotta keep her running on the higher stuff.

2005Redfire6

93.....