87+ Octane Gas vs. 91+ - HELP

[therealsteffenj]

Hi all, I went to the dealership today for my 1000 mile oil change (I know this isn't needed) and requested synthetic blend this time and will switch to fully synthetic on my 5000k oil change later this year. When I was in the service center I asked one of the techs about high octane gas and he recommended I "stay away from those 91+ octane fuels, because they do more damage then good to the 2.3L engines". Can anyone help clarify this for me? I have filled up using 93 octane from Shell (live in MA) since new. I don't want to do damage to anything but also want to do whats best for the engine to make my baby last as long as possible.

Sponsored

 

[BigHoof]

You'll have to ask the tech for clarification because Ford recommends 87 minimum with 91 or higher for best performance.

From the Owners Manual:

Your vehicle operates on regular unleaded
gasoline with a minimum pump (R+M)/2
octane rating of 87.

Some fuel stations, particularly those in
high altitude areas, offer fuels posted as
regular unleaded gasoline with an octane
rating below 87. The use of these fuels
could result in engine damage that will not
be covered by the vehicle Warranty.

For best overall vehicle and engine
performance, premium fuel with an octane
rating of 91 or higher is recommended. The
performance gained by using premium fuel
is most noticeable in hot weather as well
as other conditions, for example when
towing a trailer.

 

[Lowcountry Bronco]

I would ignore his advice since our Broncos are able to adjust up or down for the extra octane. He might have been addressing the top tier gas with added cleaners, etc but I haven't heard of that damaging the engine just your wallet.

 

[jzweedyk]

Find a new tech. Better fuel is going to harm an engine. NO

 

[RagnarKon]

Need an explanation from him.

My guess is he is saying that 91 octane will cause the PCM to apply more turbo boost, and that can cause more issues with blow-by?? Maybe? I could see how that may cause issues once the engine wears (above 100k miles). But not sure what he is getting at honestly.

 

[soldier989]

I've noticed what sounds like detonation, a clattering noise under the engine, when under load around 30mph in 3rd gear while using 90 non-ethanol from Sheetz. Maybe it's been there, and I never noticed (I doubt it, since I always drive with my windows down and am sensitive to noises). I was at half tank, filled with 93 from Marathon, and haven't noticed the noise, or it's not as pronounced. That said, I'm going to stick with top tier 93 as often as I can. I rarely see 91 in Ohio.

 

[brkdncr]

Find a new tech. Better fuel is going to harm an engine. NO

91 is not “better”, it’s just different.

 

[SHANUT]

Any octane you choose will be fine. Also, the fact that you’re changing your oil at 1000 miles to get all the crap out of there and the fact that you care about the octane, tells me you’ll have a very reliable bronco for a very long time. Enjoy it.

 

[JT58Bronc]

Octane is a huge debate and opinions vary. I am all for getting by as cheap as possible so if it will run on plain ole 87 that's what I go with. In my case I have the 2.7 and it has more than enough power to drive on the roads (and very occasional off road) at my lazy pace to keep up with traffic. It runs absolutely fine on it.

 

[RoLyMa27]

Hi all, I went to the dealership today for my 1000 mile oil change (I know this isn't needed) and requested synthetic blend this time and will switch to fully synthetic on my 5000k oil change later this year. When I was in the service center I asked one of the techs about high octane gas and he recommended I "stay away from those 91+ octane fuels, because they do more damage then good to the 2.3L engines". Can anyone help clarify this for me? I have filled up using 93 octane from Shell (live in MA) since new. I don't want to do damage to anything but also want to do whats best for the engine to make my baby last as long as possible.

Check this out.
https://www.caranddriver.com/features/a28565486/honda-cr-v-vs-bmw-m5-ford-f-150-dodge-charger/

 

[RHeinz]

91 is not “better”, it’s just different.

Thank you!

 

[5GENIDN]

Most of you probably know this... but for those that do not....

Octane.... You should be able to run anything from 87 to 93.... Lower octane (87) will explode under pressure sooner than higher octane (89). The higher the octane the higher the pressure before the gasoline self ignites. You do not want the gasoline self igniting before the engine is ready. That is called pre-detonation or "knock". So higher octane gas can be placed under higher pressure for longer without pre-detonating.

Modern engines sense "knock" and can adjust timing (when the valves open/close/spark etc...) based on whether is senses "knock". This allows the engine to gain higher horsepower and torque from a higher octane gas, while still able to run on lower octane gas just at a reduced output.

DO NOT confuse this with top tier fuel.... Two very different things.

"Top Tier" fuel is a name auto manufactures and gasoline producers came up with in the 90's??? I think. "Top Tier" simply means the gasoline you are purchasing has a given minimum level of cleaners/detergents as additives to the gas. If you have ever torn apart an engine or seen an engine torn apart you will see carbon build up, often on valves. That build up becomes hot spots and interferes with air flow. The cleaners help minimize this build up. Direct injection bypasses the valves so they do not get those cleaners in the gasoline/air flowing over them. This was a real problem in the early 2.7 engines. That is why FORD then changed the 2.7 from direct injection to a combination of direct injection with some port injection. The Port injection is not quite as efficient as direct injection but it gets those cleaners across those valves...

This is why I will always run "Top Tier" gasoline no matter what Octane I use. And yes I like the higher out put so I will run a higher octane.... BUT I will typically try to run the same octane (when ever I can)... Every time I change octane the engine will have to adjust the timing and I might get some "knock" while it is doing that... The computers and the sensors are pretty quick these days though and I probably will never even notice any "knock".

Just my take on gasoline.
I am a simple guy and I think of things in simple terms, I am sure there are people on here that know more about it than I do.

 

[GTTom]

Check this out.
https://www.caranddriver.com/features/a28565486/honda-cr-v-vs-bmw-m5-ford-f-150-dodge-charger/

Good article! Nice they included the Ford F150, though that had the 3.5 V6. 20HP difference between 87 vs. 93 octane.

 

[PolarVortex]

Great writeup Joe.

FWIW, here in VA we have Sunoco (a Top Tier) which has four choices of octane - 87, 89, 91, and 93. I just got my Bronco and it's got the 2.7 which I love. The free tank of gas from the dealership was nothing special and it didn't feel right to me, like the Bronco was holding back slightly. The engine sounded just, ok, but no loud knocks or anything. So I put 93 in it when I got it as empty as I could, comfortably. Since then I've noticed a slight improvement in the acceleration and general performance and the engine sounds better. I agree it's not a good idea to jump from one octane to another too much so I won't do that, but I may try a tank of 89 or 91 just once in a while to compare.

In the meantime, the price difference works about to be about $5.50 a fillup more with 93 than 87. I worked out that it's around $265 per year more to use 93 over going with 87 at today's price by me, with my commute and number of fillups (about once a week).

At the moment, I'll stick with 93 whether it's a placebo effect or not, as that seems like an ok trade-off to me.

 

[Alfa]

I get 10-15% better gas mileage from 93 vs 87, so that subsidizes the cost when I get 93.

Sponsored