You're welcome. I also get a lot of useful informations from this forum.
Let me explain what I've experienced more in detail. I had purchased my Z in the early 2012, and from the first I just had put the cheapest gas as found anywhere nearby. At that time I had no idea about the fuel additives, I just wanted to pay less as possible for very expensive gas prices at that time. (It included Arco, but I must have visited many non-top tier cheap gas stations I guess - of course always premium though
)
Later one day I found out I got to have somewhat lower throttle on my Z especially when I try full acceleration for zero to sixty entering freeway from local. So what I did was that I put a Valvoline and Techron (by the Chevron you know) engine system cleaner to my Z, and very soon I got back its whole faster response as I had at the first time.
My last report from Blackstone says the engine looks in pretty good condition now.
By myself I've tested many brands of premium gas (like 76, Shell, Chevron, Mobil .. etc) to my Z, but as a result interestingly I found out that I had the best performance with Arco premium (it is by my subjective feeling, not by any objective measure). If it is true, it must be because my engine already got used to the Arco gas, so other Zs might go different.
As I know any engine is supposed to get used to a specific brand of gasoline because of its different additives. I think Arco gas is okay, but what matters is that you really need to put high octane - I mean premium gas to your Z.
I agree Shell or Chevron are more expensive and maybe better than Arco, but absolutely Arco premiums should work far better than those regulars on your Z.
Or if you want to take care of your engine better, you can also try those engine system cleaners. I cannot guarantee it would work to your engine, but it really worked to mine when it was little messed up with putting cheap gas. (I recommend you to be careful to choose what engine cleaner to use, because bad cleaners might do harm to your engine)
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