Gas quality. Is cheap low octane gas as good as expensive low octane gas?

MyFirstMazda

MyFirstMazda

:
2018 CX-5 Sport
I go to a gas station that has lower prices than anyone else and I get 87 octane. But I started thinking, will cheap gas leave more carbon build up on the valves and pistons? What is your opinion about gas?
 
I dont feel like it matters. I never cared. Hundreds of thousands of miles, and its never mattered. My father has driven millions. He prefers Shell, but oil preference is his main thing. Tore down every motor he wore out in the 80s and early 90s. Oil is where he saw the difference.
 
Ive always had some hesitation using any ethanol added on my fuel. We had a 99 Honda Odyssey that had issues (check engine light) with it. Service dept told us to avoid using ethanol because that was an issue with all the emissions error we were getting. YMMV.
 
Ethanol free is so damn expensive here, like an extra 60 cents a gallon. Id use it in my cars if I could, but due to the price premium its used only in my lawn equipment.

I agree with the direct injection thoughts as the extra detergent never comes into contact with the valves on our engines. Top tier stuff probably does help keep the injectors cleaner too. I can say from experience that gas with higher detergents made a big difference with carbourated engines. My 69 Impala I used to have would get idle issues due to crud buildup in the carb. Marvel mystery oil added to the gas would clear it up, and the problem wouldnt come back until I started using cheap gas again.
 
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MyFirstMazda said:
I go to a gas station that has lower prices than anyone else and I get 87 octane. But I started thinking, will cheap gas leave more carbon build up on the valves and pistons? What is your opinion about gas?
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Even with our direct-injection engine and fuel can't reach the valves, people should still use the top-tier gas at all cost. I use Shell regular all the time on my CX-5, although top-tier Costco gas is the best alternative available with low price and high quality detergent pack.
 
Personally I do stick with top tier as well and typically get Phillips 66. Im just not sure how much it matters with these newer engines.

Ethanol was a problem with the older cars not designed for it. I wouldnt worry about ethanol on modern cars as long as its not over the % it was designed for.

Where I live ethanol free is very rare.
 
I am going to use top tier from now on. You guys say that the gas never touches the valves. How is that possible? In the least the dirty exhaust passes past the valves and valve seats.
 
In a direct injection engine the fuel is injected directly into the combustion chamber. This is unlike port injection where the injector is in the intake.

But you know Jason from EE can explain it better than I can.

https://youtu.be/nbCe68ck6qg

Side note. Jasons production quality has come a long way.
 
Top-Tier, for the most part, is all marketing. An example is BP. They held out for years, but finally gave in and joined (paid) them. They changed nothing in their fuel formulations.
 
If anyone has a concern about carbon or other intake valve contamination you can easily cure ,rid or just keep the intake valves complete clean with a water/meth system. These can easily be installed in a few hours even for DIY. They are a great investment and you can remove the system at anytime and install on other vehicles.
 
yrwei52 said:
Even with our direct-injection engine and fuel can't reach the valves, people should still use the top-tier gas at all cost. I use Shell regular all the time on my CX-5, although top-tier Costco gas is the best alternative available with low price and high quality detergent pack.
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This certainly applies to diesel cars in Europe. The supermarkets sell weasel pee which is not cheap because the supermarkets are showing loyalty or friendliness, it*s because they lack the additives that branded fuel has. What I would add is that the vapours that enter the inlet manifold via the crankcase ventilation system are made up from oil and also fuel and exhaust that gets by the pistons. It*s a nasty cocktail of corrosive substances and even more reason why good quality fuel and regular oil changes are paramount on the modern day low emission direct injection engines.
 
ruthrj said:
Id use it in my cars if I could, but due to the price premium its used only in my lawn equipment.
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Now that's just wasting money. Your lawn mower doesn't need better gas then your car does.
 
Fortunately carbon buildup doesnt seem to be a big issue with Skyactiv like it was on the MZR motors.

Personally Im not to worried about it. And will continue with to use top tier gas. I keep telling the wife to stay away from that cheap grocery store gas.
 
7eregrine said:
Now that's just wasting money. Your lawn mower doesn't need better gas then your car does.
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Have you seen his mower?
Honda-Mean-Mower-gear-patrol-full-lead.jpg


:)
 
7eregrine said:
Now that's just wasting money. Your lawn mower doesn't need better gas then your car does.
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How so? I use about 4 gallons of gas a year to run my ride on mower, so I paid an extra $2.40 for ethanol free gas. It sits much longer in a tank that is not sealed well, thus exposed to humid FL air. Ethanol + H20 = no bueno. Dont want the ethanol soaking up water, and the engine runs stronger and smoother with straight gasoline. Its amazing how fast E10 goes bad in a mower tank. And as much as I like Briggs and Stratton engines, even their modern designs dont handle ethanol well. My first ride on mower needed the engine rebuilt after 5 years of use because the E10 took out the seals.
 
jthj said:
Fortunately carbon buildup doesn*t seem to be a big issue with Skyactiv like it was on the MZR motors.

Personally I*m not to worried about it. And will continue with to use top tier gas. I keep telling the wife to stay away from that cheap grocery store gas.
Click to expand...

In the USA there is not really low or high quality fuel. Each fuel has a federal standard requirement and then depending on the supplier their additives that they headline for their fuels. I personally use Chevron.
The best way to explain it is visualize several FULL fuel tankers with all the same refined fuels all pulling up to a DRIVE THOUGH THAT ARE MARKED, Costoco, Shell, Chevron, BP, ETC....AS THEY GO THROUGH EACH TANKER GETS IT "SNAKE oil" special additives that go along with the who they are going to be delivering the fuel to like Chevron Techron, Shell- nitrogen-enriched, etc.

You should use the fuels in your country that the auto manufacture recommends. This is generally a Low octane fuel. You seldom will see any gains using higher octane fuel for normal daily driving. So there is no advantage to using them unless the retirement states other wise.
There is so much MYTH floating around on forums and the internet regarding what fuels to use and really I say MYTH. So much changed in the USA regarding fuel standards, unless you use a "Race Fuel" about 20+ years ago.
I try to stay with using the same station (Chevron)and the same pump and will always look for current certification stickers and any parts that were changed on the fuel nozzle I normally use. Mostly to keep a better accuracy of my fuel use log.
 
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