POLL: Will 85 Octane Ruin The Bronco?

[Mdsuits]

I accidentally put in once….ran fine, but at half a tank I topped it off with 91. In a turbo vehicle I don’t think I would risk doing it on a regular basis….and technically the manual does say 87 or higher.

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[dgorsett]

Following. I have run 85 in all my Fords that recommend 87 to no I'll affect. However, I now run 87 in my EB Bronco and Explorer. Folks have made a good point that turbocharging simulates a lower altitude. But, it won't blow up, put 85 in by mistake a week ago.

 

[TheShark]

No, 85 octane. It is common out west. Every station here has it.

You learn something new everyday, had no idea living on the right coast.

 

[Aonarch]

As others have said, what worked previously with carbureted or naturally aspirated engines doesn't work on engines with turbos. And both of the Bronco's engines have turbos.

Octane rating signifies the fuel's resistance to pre-mature detonation. At high altitudes, the air is less dense, which means less oxygen in the air, which means it naturally is more resistant to detonation than air at lower altitudes. But if you have a turbo compressing the air, none of that is valid.

In theory... the knock sensors should save the engine from destruction. But I wouldn't make a habit of it and generally wouldn't try it outside of emergencies.

Yup! I run it in my 1996 Isuzu Trooper, but wouldn't in the Bronco.

You are spot on. In theory, yes 85 is a good substitute for 87 since I at least never drive below 5000 feet of elevation. But with the turbos, they are making up for the loss of air density.

 

[CarmeloS]

You spent $50+k on a badlands, and wanna cheap out? This isnt a versa or sentra now

 

[brkdncr]

Might invalidate the warranty.

 

[JerryG]

I run a blend of 1/3 E85 and 2/3 93 octane with a BMS tuner tuned for it. The power increase over 93 is very noticeable.

 

[mpeugeot]

I ran 85 octane at altitude to see if it would knock or ping, it didn't, it was fine. However, in a turbo motor, especially in the heat of summer I would still pay a little more for higher octane fuel in a turbo motor.

 

[cjacobalpinetx]

You can at higher al higher altitude run lower octanes. Its bery common. Air density is thinner at elevation. Even turbo charged.

The bigger question is with an engine thay is boosted and tuned for 91+ why allow the motor to retard timjng to accommodate a lower octane?

i have 1 station in my town that sells 91. The other is 85/87/89 and not top reir.

i would burn the top teir higheat octane i can buy. You MPG is ill increase at altitude due to the tinner air.

 

[kodiakisland]

Well, you can tell who has never driven out West.

East coasters be like:

 

[Sitruc_btb]

A poll? Like winning the poll establishes truth?

It's the American way.

 

[Tricky Mike]

I used 85 octane all the time when living in Colorado no issues. My understanding was at higher altitudes, the lower air density meant less likely to pre-detonate (knock), hence 85 octane at higher altitude was like 87. (But I didn't own turbo engines.)

My hunch is it would be fine for that reason. I filled up in a high elevation town a while back and considered the 85 but because I was going to be back to lower elevation before I burned it off I paid the extra for 87.

 

[Muffin Top]

If you're not putting a lot of mileage on it then you'll want higher octane. Cold-start octane fades rapidly. As others have mentioned, octane is also more important with turbos.

 

[Gregus73]

I run 91 since there is a turbo.

Have always ran 91 on turbos…same on my past Porsche and Cadillac V series.

 

[thepear]

Well the other thing I’m wondering is how many people out here with eco boost Fords just hitting the 85 octane and calling it a day? Are most people pressing the middle option or just looking past the number and press the cheapest option. Are the systems smart enough to not damage the engine but just reduce the power and perhaps gas mileage? I make sure to use 87.

I’m pretty sure the Ford dealership that I purchased the Bronco from filled my tank with 85

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