How is Marathon gas compared to Shell?

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jlb32
Posts: 12
Joined: Fri Feb 03, 2017 7:36 pm

How is Marathon gas compared to Shell?

Post by jlb32 »

Better to run the 91 octane tune with 93 octane gas or better to stick with the 93 octane tune with 93 octane gas?

I've heard Shell gas is crap but after several fillups with Marathon gas it doesn't seem any better or even as good as Shell?

I am currently running the 93 octane tune. Just wondering if I should install the 91 octane tune and see if I like it better?
jlb32
Posts: 12
Joined: Fri Feb 03, 2017 7:36 pm

Re: How is Marathon gas compared to Shell?

Post by jlb32 »

I went ahead and installed the 91 octane tune on my GTO over the 93 octane tune I had been using. Guess we will see if the 91 tune performs better than the 93.

I am thinking about going back to using Shell gas over the Marathon. The Marathon gas seems to not work as good as the Shell, even though Diablo says Shell gas sucks.
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06MonteSS
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Re: How is Marathon gas compared to Shell?

Post by 06MonteSS »

Make sure you are using GOOD 91/93 octane gas, it makes a difference... mobil, exxon, sunoco, amoco, bp, chevron are best brands to use, with mobil and exxon being the best..

NEVER use Shell, costco/bj's, mom-n-pop, or no-name brands, as it's crap gas that tends to cause a lot of knock retard and less performance/mpg...
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jlb32
Posts: 12
Joined: Fri Feb 03, 2017 7:36 pm

Re: How is Marathon gas compared to Shell?

Post by jlb32 »

Thanks! In my area it's pretty much Marathon, Gulf or Shell gas. All offer 93 octane.

Which would you suggest as the best of those 3 for me to use?
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