91 octane ok? 93 only?

[Vakane]

What’s the verdict

Some people say 91’s ok….

Now it actually makes a didference in price between 93 and 91!

 

[Bigfx]

Always 93 unless you can’t get it, the higher the octane the better your car will run. Turbo charged vehicles really need to always have the highest octane available. Now if 91 is all that’s available then that’s what you can do, but 89/87 are imho not good for the car.

 

[Vakane]

I didn’t even think it would run 89 or lower…. It seems like a car that only runs premium 93

 

[MatthewAMEL]

The higher octane rating is extremely important to FI cars.

Octane is a measure of resistance to ignition. Pre-ignition in FI cars can be really, really bad.

Search for LSPI if you want a scare/more info. It’ll also explain why you never lug a FI engine.

If you are out west and 91 is the best you can get, don’t worry. But if I were to take it to the track, I’d either throw in a couple gallons of 98 octane or some Torco.

 

[RDATLTE]

What’s the verdict

Some people say 91’s ok….

Now it actually makes a didference in price between 93 and 91!

The factory HP & TQ #s are on 93. You can use 91 but, it'll pull some timing and you won't have quite the power that 93 would give you. You'll more than likely not get as good of gas mileage as well.

 

[Finally-a-V]

Out here in AZ, and points west, 91 is the best you can find. I believe the "book" says 91 or better.

I don't ever plan on running anything but premium in my BW, unless I don't have a choice. I can tell you, I've been running regular in my Expedition for a while, and it seems sluggish. Switched that back over to premium.

 

[Ryan]

Let’s separate this into two parts.

First, the energy density, or lower heating value of 91 and 93 octane are identical. In fact, it’s the same for 87.

Secondly, the engine control logic is constantly monitoring knock and adjusts engine timing on the fly.

You can not dial up the overall compression ratio as high on 91 vs 93 octane, and thus you can’t make as high of absolute power. However, your mileage should be equivalent within measurement uncertainty. Maximum efficiency is way dialed back from maximum torque.

While not recommended, your engine will run fine on 87 if you accidentally put that in. It will sense the knocking and retard the cycle timing. Don’t put diesel though…

 

[rdollie]

Out here in AZ, and points west, 91 is the best you can find. I believe the "book" says 91 or better.

Costco here on WA state has Top Tier 92 octane