What grade of gas does your large gas engine require

[invmartyc]

With the big V-8 and V-10 engines do you have to burn a higher octane than regular unleaded? Back in the days of muscle cars you had to burn premium.

Does that apply to big blocks in RVs?

[ljr869]

The regular stuff is called for but I use mid-grade.

[rk911]

ford f53 super duty....87 octane

[kalynzoo]

My current Workhorse 8.1 runs fine on regular, even the real low grade stuff, like 85 octane which we often find in our travels. My previous Ford V10 used regular, previous to that the 454 used regular. Never noticed a knock even over the mountain ranges we travel out here in the West.

[jcthorne]

wa8yxm wrote:
I do not think they make a production engine any more that needs more than Regular (87 octane) gasoline.

now if you go out and buy a high performance sports car.. With the custom higher performance engine option, and you modify the engine on top of that.. Perhaps.

But for what I call production engines, Used in normal cars, trucks and motor homes... I think they all burn regular.

Only exception I know of is the Chevy Volt.

There are a large number of turbocharged and supercharged regular production vehicles (not motorhomes) that require 91 octane gas as do most motorcycles.

The Ford Ecoboost engines are a broad exception, they all run on regular gas despite the forced induction due to Fords patented use of exhaust gas recirculation to control flame front propagation. This is one of the main technologies that makes Ecoboost engines different from other generic turbocharged small gas engines.

[jimrose]

I got this off the internet about 85 octane.

Q:
I live in Arizona and use 87-octane regular. In Utah, Idaho and Nevada, stations were selling 85-octane as regular gas. This forced me to pay more for midgrade 87-octane. Is this the latest petroleum-industry scam to get more of our money? Will my car run okay on this bogus 85-octane regular?

A:
Octane is the ability of a fuel to resist knock, and high-compression engines tend to knock more. The obverse of that is that lower-compression engines can run on lower-octane gas. Air is thinner the higher above sea level you go. Less air going into the cylinders means less pressure at top dead center when things go bang. It's a lot like lowering the compression ratio in the engine, reducing the need for high octane. Cars will run just fine on lower-octane fuel when they're well above sea level--and all of those states are. Hopefully, by the time you get back down to denser air, you've burned off most of the low-octane stuff, and can refill the tank with higher-grade fuel.

[wa8yxm]

I do not think they make a production engine any more that needs more than Regular (87 octane) gasoline.

now if you go out and buy a high performance sports car.. With the custom higher performance engine option, and you modify the engine on top of that.. Perhaps.

But for what I call production engines, Used in normal cars, trucks and motor homes... I think they all burn regular.

Only exception I know of is the Chevy Volt.

[cochise49]

Ford Manual and Winnebago manual says 87 octane in the tank for the Triton V-10. Can anyone explain to me why 85 octane is sold at the higher altitudes? We have a home in Ely, NV where that octane is sold. Always wondered why when manufacturers have called for 87 octane minimum for many years.

[AllegroD]

Rergular. 87 - 85

[rvten]

I have used just plane old Reg.
Used it in all my gas MH's. Chevy 454, 7.4 Vortec, 8.1 Vortec, and this V10.

[rgatijnet1]

87 or 85 if it is available at higher altitudes.

[BobR]

Old Ford 460 running 87 octane per owner's manual.

[K_Charles]

The compression ratio is only about 9:1 so you can use regular gas. They have found better ways to make power then raising the compression ratio.

[gbopp]

Our 96 Southwind, 454, works great on 87 octane.

[dayakster]

The previous owner of my 97 Allegro Bus said he ran regular too. Thanks for the question as I was in need of opinions also.