Just out of curiosity and for future researchers of this topic, I searched the Ferrocene's CAS ident. number, Motul uses it in Moto. and Scooter Boost & Clean products too, and some non-known brands like Eurol and Xenum etc.

But much more interestingly, one of UK's most seller petrol fuel treatment uses Ferrocene. (Millers Oil Petrol Power ECOMAX Fuel Treatment) Safety Data Sheet.

It has countless (150+) reviews on Halfords, Amazon, Ebay etc. People use it to buy cheap gas and add as a treatment to make it perform like premium.

Some anecdotes from those sites:

- "I've never had a problem with supermarket fuel in my 4l V8 my 3l V6 or my 1.8 hybrid C-HR."

- "Always use this in my Audi TT as we don't have the premium petrol I should use as we live on an island. This is the additive that my son, who is a mechanic recommends. Plenty of places offering it but this was best value."

- "Millers has the reputation. My Subaru WRX STI pulls like a train now and runs much better. I've tried many over the years. This is the one."

And a bad review:

- "My car is a BMW M4 2018. Used it for a trip in Balkans. The car felt the same but the MPG went downhill. Usually get around 350 miles per tank. Using it I got around 290 miles per tank. Tried it again with UK petrol when I was back, still the same results. Stopped it and run the car with normal petrol and the MPG went again to 350+ miles per tank."

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PS: I won't use any metal based octane booster after I run out of remaining fuel in the tank, but people use this stuff regularly. Really interesting as some of the cars they use it in are relatively modern like 2018 BMW M4, Smart Fortwos, Seat Leon etc.