Dks01 It’s not that it’s not available, it’s that Shell is willing to pay the fees to the Top Tier org for “certified” testing that the Esso and Petro already do for their additives. It does not mean that Shell gas is better than either of other two because it’s “Top Tier”. What matter is the additive package, not the marketing designation. For example Esso gasoline in Canada contains additives that are not legally required by regulation, and are missing from off-brand gasoline, one reason for the cheaper price there. Shell has very similar if not identical additive package.
- Solvent Fluid #1 – keeps additives mixed and flowing in cold weather
- Solvent Fluid #2 – delivers detergents efficiently
- Anti‑Adhesion Compound – prevents sticky films on intake valves
- Corrosion Inhibitor – protects tank and fuel‑system metals
- Demulsifier – prevents water from mixing into the fuel
- Fuel Detergent – cleans intake valves and injectors
- Marker Molecules – ensure correct additive dosing
https://www.esso.ca/en-ca/unleaded-gasoline
GM recommends “Top Tier” gas to reduce valve deposits.
https://static.nhtsa.gov/odi/tsbs/2013/MC-10118858-9999.pdf
If your vehicle is port fuel injected or has direct and port injection, atomized gasoline is sprayed on the intake valves during the combustion cycle, so they get “washed”, reducing carbon buildup. This means gasoline cleaning ability is not as much of a concern as it is with a GDI engine.
