Fuel Injection Cleaning and Induction Service - 50k miles

I think you made the right move in declining it. My Prius had 20,000 miles on it and that is the same pitch my dealer gave me. I was having a senior moment and I let them do it. I have since changed dealers for a couple of reasons and the dealer I now have does not seem to rip me off for unnecessary things. YET.

 

When i bought my car i ran about atleast 10 to 15 tanks of 93 grade gas and then did research n found out i dont need higher octane. It did reduce my mpg. Started putting regular 87 which improved mpg. But i make sure that i always use tier 1 gas not just any brand, i prefer shell which is tier1 and has higher level of detergents resulting in less likely buildup of carbon.

 

In general, Prius 3rd gen can get benefit up to octane 89 or midgrade. Above it, the benefit is not much. Ocassionally I heard rattling/pinging from mild detonations on my 2nd gen Prius and 2004 Sienna with 87 regular. It reduced significantly when I use premium 93 gas from Shell. I believe the reason is running too lean with E10 10% ethanol, when government forcing us in 2008. Cars pre-2008 was designed for 0% ethanol and it shift the mixture too lean and create mild detonations (sounds like rice on aluminum foils). I experience it on: Camry 2002, Altima 2002, CRV 2003, Prius 2006, Sienna 2004. But E10 works fine on my 3rd gen Prius engine in Auris hybrid 2015, PriusC/Yaris 2014, Golf 2017, etc. Although I still prefers E5 because 1-2% more power with price difference also 3-4%. E10 kills catalytic converter faster than E5 or no Ethanol.