The evidence for using Top Tier fuel is very compelling to me. I will never use non-Top Tier fuel in anything I own again.
Gasoline study by AAA on effectiveness of quality detergent gasolines and others.
The basics -
AAA: Not All Gasoline Created Equal | AAA Newsroom - "
Tests show quality gasoline keeps engines 19 times cleaner"
In depth -
http://www.aaa.com/AAA/common/AAR/files/Fuel-Quality-Full-Report.pdf - results summary starts on page 24.
"Gasolines with an enhanced additive package demonstrated a clean-up performance (reduction of intake valve deposits) ranging from 45 percent to as much as 72 percent in the 5,000-mile test. The variation in cleaning performance was primarily based on the concentration of the additive package in the fuel. "
"Key Findings
1. The test engine operated on a TOP TIER gasoline averaged 19 times fewer intake valve deposits than when it was operated on non-TOP TIER gasoline. (based on the ASTM D6201 test -TOP TIER gasoline averaged 34.1mg of deposits per intake valve versus non-TOP TIER average of 660.6mg)
2. Based upon secondary research findings, long-term use of a gasoline without an enhanced additive package can lead to reductions in fuel economy of 2-4%, drivability issues, and increased emissions.
3. In most cases, carbon deposits can be reduced or removed from critical engine components by switching to a gasoline that meets TOP TIER standards.
5. Most TOP TIER gasolines do not cost significantly more than non-TOP TIER gasoline. The average price difference between the TOP TIER and non-TOP TIER brands surveyed was three cents per gallon over a 12-month period."
Top Tier fuels - TOP TIER™ Gasoline Brands
Common TOP TIER™ Licensed Retail Brands (incomplete):
Amoco with Invigorate
BP with Invigorate
Chevron
CITGO
Conoco
Costco Gasoline
Express
Exxon
Kwik Trip (Express)
Mobil
Phillips 66
QuikTrip
Shell
Standard
SuperAmerica
Texaco
less common brands to use :
76
Aloha
ARCO
Beacon
Break Time
Cenex
Co-op
Country Mark
Diamond Shamrock
Esso
Hele
Holiday
Kwik Star
Mahalo
MFA
Ohana Fuels
PUMA Maxxima
QT
Road Ranger
Shamrock
Sinclair
Superfuels
Tempo
Tri-Par Qwik Stop
Valero
Common brands NOT to use: Speedway, Love’s, Casey's, and Sam's Club.