87 Octane is OK for 6.4L Hemi?

[Gondul]

It’s amazing how many Hemi owners I know or have met here in Colorado that have no idea they are supposed to run Colorado mid grade which is 87, and they have been running 85 since their trucks were new with zero issues. Never made sense to me that that FCA doesn’t put something on the gas cap about the fuel grade like my wife’s Lexus has. Do they really think people are going to read the owners manual before pumping gas?

Given the number of questions posted here an on FB... that answer would be 'very few'...

 

[ColoradoCub]

Given the number of questions posted here an on FB... that answer would be 'very few'...

Yup, there are thousands of 6.4 and 5.7 Hemis running around the mountain west using Regular 85 octane gas with no issues.

 

[jsalbre]

Yup, there are thousands of 6.4 and 5.7 Hemis running around the mountain west using Regular 85 octane gas with no issues.

I supposed that depends on what you consider an “issue”. I’m of the opinion that making less power than advertised is an issue. You’ve already got power loss from altitude too.

 

[ColoradoCub]

I supposed that depends on what you consider an “issue”. I’m of the opinion that making less power than advertised is an issue. You’ve already got power loss from altitude too.

When I say no issues I’m referring to the mindset that somehow 85 octane above 5000-6000 ft is detrimental to these Hemi engines themselves or that they would ping and rattle from the lower octane. I see plenty of these trucks hauling campers and trailers full of toys up and over 10,000-11,000 ft passes too. I’m not advocating that these trucks will or won’t make the same power running 85 or 87 or 89 octane, just simply speaking to the octane requirements in the manuals, the cautions, and the difference between sea level and high altitude. A little Food for thought, tests have been done that show that 85 octane at 5000 ft (which is actually low altitude here in most of Colorado) performs better than 87 octane does at sea level.

 

[bidenntrumpp]

I finally drove the truck on a 500+ trip empty, Speeds to 75, most speeds at 65, and over three high mountain passes. Evic read 18.7 but actual mileage was 18.26 I don't think I could beat that with the higher octane.

 

[Electronut]

I finally drove the truck on a 500+ trip empty, Speeds to 75, most speeds at 65, and over three high mountain passes. Evic read 18.7 but actual mileage was 18.26 I don't think I could beat that with the higher octane.

That's crazy fuel mileage on this HD truck. What rear gearing you have? Can't believe 4.10 gearing gets so much less. Quite a large gap.

 

[ColoradoCub]

I finally drove the truck on a 500+ trip empty, Speeds to 75, most speeds at 65, and over three high mountain passes. Evic read 18.7 but actual mileage was 18.26 I don't think I could beat that with the higher octane.

I can believe that , I’m averaging 15-17 with my day to day running around to include a partial highway commute. I don’t live in a big city though. I’ll be taking my first road trip next week , 900 miles round trip abd am anxious to see what I get.

 

[Gondul]

I barely get 16 (hand calculated) on the highway doing 70 in Flori-duh...

 

[ColoradoCub]

I barely get 16 (hand calculated) on the highway doing 70 in Flori-duh...

This is pretty typical for me mixed driving

 

[ColoradoCub]

I finally drove the truck on a 500+ trip empty, Speeds to 75, most speeds at 65, and over three high mountain passes. Evic read 18.7 but actual mileage was 18.26 I don't think I could beat that with the higher octane.

Just got back from a 400 mile trip from Utah to Colorado, 3 mountain passes and 90+ deg temps. two 100 lb dogs in the back seat me and the wife and a bed full of stuff, never turned the truck off , not even when we had lunch. My 6.7 2500 got .8 mpg better on this same trip in the past.