Fuel tips: Additives, octane, ethanol and more.

By Colin Wood
Aug 30, 2021 | Fuel Tips, Fuel Facts

Should you use fuel additives? Do you have options if 93 octane isn’t enough? How much ethanol is really in that E85?

If you’ve asked yourself any of these questions, it's been answered by Sunoco technical specialist Zachary Santner as part of our Fuel Tips and Fuel Facts series, which you can read in their entireties below.

Fuel Tips from Grassroots Motorsports:

What separates a race fuel from a street fuel?
The science of high-octane fuel
What happens to gasoline as it ages?
Ethanol or not for your gasoline?
Does all E85 contain 85% ethanol?
Why does E85 run cooler and make more power?
More oxygen for more power?
Why not methanol?
Picking the proper gas regarding lead and oxygen
Narrowing the fuel field
91 vs. 93 octane
Why top tier street fuels matter
Fueling your boosted engine
What fuel to feed a rotary engine?
Lawn and garden equipment needs the proper fuel, too
What is vapor pressure of gasoline and why should you care?
What is specific gravity of gasoline and why should you care?
Adding additives to your fuel. | Yes or no?
What's really in that fuel additive?
Antioxidants, fuel stabilizers, and you
Winter fuels for wintertime
Fuels for a post-apocalyptic world
Need help selecting a fuel? Call the experts.
Gas station basics that aren’t that basic

Fuel Facts from Classic Motorsports:

What is race gas?
Which race fuel is right for you?
Buying and storing race fuel
The right fuel in the fall might help your engine start in the spring
Fuels for storage: good, better, best
How much octane is enough for my classic?
93-octane not enough? Solutions exist.

Can you blend fuels to get the right mix?
Tuning for today's oxygenated fuels
Picking the proper gas
How to choose a quality gas station
Why is there ethanol in our gasoline?
Why not avgas in your car?
Water is great for your plants, not so much for your fuel system
Gasoline makes a terrific degreaser, yet this practice can kill you

And, in case your question isn’t answered above, post it below and we’ll be sure to ask our friendly neighborhood fuel specialist the next time we give him a ring.

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View comments on the GRM forums
Colin Wood
Colin Wood Associate Editor
8/24/21 2:36 p.m.

This might come as a surprise, but one of the biggest things I learned from these is that just because it's labeled E85, doesn't mean it gas 85% ethanol.

I know, might sound like a given, but I guess I just assumed it would always have that much ethanol in it.

frenchyd UltimaDork
8/24/21 2:48 p.m.

In reply to Colin Wood :

Our pump stickers actually say 51-85% ethanol.  Later in the summer it's usually near 85% in winter it's closer to 51% 

  But that's not the only problem. The 15%  that is gasoline can be pretty poor quality gasoline.  
Hence the need to buy from a racing source. To get 85% ethanol and high quality  gasoline.  
  That or have a flex fuel sensor measure and do the timing and fuel quality adjustments for you. 

David S. Wallens
David S. Wallens Editorial Director
8/24/21 3:00 p.m.

Sames, the E85 talk has been among the bigger surprises for me. "You mean that E85 can contain only 51% ethanol?"

JG had been running our Corvette on E85 from the corner station. Then we got some Sunoco E85-R for Time Trial Nats. 

"So, um, what's the other 15% of that stuff?" he asked me. "Rocket fuel?"

So I asked Sunoco: The gasoline component of E85-R is almost 100 octane race fuel, not 85 octane low-grade. smiley

alfadriver GRM+ Memberand MegaDork
8/24/21 3:03 p.m.

In reply to David S. Wallens :

Man, I HOPE it's not rocket fuel- that would be a terrible choice.  That's just very  pure kerosene- which has a pretty low octane rating.  Good cetane, though.  

I know it's a passing joke, but it's interesting how people think that "rocket fuel" is so potent for a gas engine.

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