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does anyone use octane boost/fuel injector cleaner? been wondering if these C8 cars get dirty injectors over time even with Tier 1 gas only
Absolutely do not use octane booster. They're not recommended and will leave a permanent indicator that they have been used.
Approved cleaners are ok. AC Delco has one that is the same as the bottles of techron you can buy at auro parts stores just a different label. GM dealerships also often use bg44k.
There should be no reason to use them if using top tier fuels
They still give owner's manuals with vehicle these days?
The 2020 Owner's Manual (SEE BELOW) says clearly IF you use 91 octane it will REDUCE PERFORMANCE AND FUEL ECONOMY.
Can speculate that is not the case with later year C8s BUT IMO GM just changed the words to make folks who can't get 93 Octane "FEEL BETTER." Don't think some understand that the GM engineers pushed the small block from what I had in my '56 using the exact same bore spacing and using 11.5:1 compression. Back-in-the-day 11.5:1 compression would have required Sunoco 260 with 100+ octane and a Duntov cam with so much overlap it kept actual compression down when the engine was operating at lower rpm where knocking was more likely to occur! Could always tell a Duntov camed engine with its lumpy ~900 rpm idle!
Yep the C8 air/fuel MAPS can adjust and make the fuel air mixture richer to reduce knocking BUT that can only go so far. AND you'll sacrifice power and fuel economy! The LT1 in my C7s also had high compression, the same cid, variable cam timing (best you can do with only one cam) AND that Owner's Manual said, quoting: "Use premium unleaded gasoline with a posted octane rating of 91 or higher. If the octane is less than 91, you could damage the engine and may void your vehicle warranty." BUT that was before pushing the LT2 with 35 MORE HP.
Folks where only 91 octane is available can believe what they wish and you're probably not losing a lot of HP and fuel economy BUT doubt GM did anything but change the words in later Owner Manuals!
..... doubt GM did anything but change the words in later Owner Manuals!......
Probably not a change to the engine, but did cause a change in the specified fuel (regular instead of premium) used for the EPA fuel mileage measurements. The fuel mileage between 2022 and 2023 did not change, but its now achieved on regular fuel, and the annual fuel cost is lower. Also, note that between 2021 and 2022 the fuel mileage changed. Curiously, the hwy miles went down, 27 to 24, and city miles went up 15 to 16. I don't know how they are weighted but the combined mileage did not change. That change from 2021 to 2022 was, I think, due to a change in the fuel management in the engine. No change was stated for hp or torque.
Funny how for 2020-2022 the total cost was the same - with the same combined mileage. They must have used the same cost per gallon for all three model years. Then its lower for 2023, not because of a change in combine mileage, but due to the regular fuel being cheaper.
Probably not a change to the engine, but did cause a change in the specified fuel (regular instead of premium) used for the EPA fuel mileage measurements. The fuel mileage between 2022 and 2023 did not change, but its now achieved on regular fuel, and the annual fuel cost is lower. Also, note that between 2021 and 2022 the fuel mileage changed. Curiously, the hwy miles went down, 27 to 24, and city miles went up 15 to 16. I don't know how they are weighted but the combined mileage did not change. That change from 2021 to 2022 was, I think, due to a change in the fuel management in the engine. No change was stated for hp or torque.
Funny how for 2020-2022 the total cost was the same - with the same combined mileage. They must have used the same cost per gallon for all three model years. Then its lower for 2023, not because of a change in combine mileage, but due to the regular fuel being cheaper.
Where can you find 91 octane regular? Doesn't the 2023 manual say 91 octane premium is required? How can they have an EPA fuel rating using a fuel that is prohibited by the owner's manual?
