[NGT2]

I use Shell 93 when I can but will use whatever big name is around, but always 93. In the south, I never see 91.

I use the same premium 93 for my M550 and X7 40i.

[BMW5and7]

Costco gasoline has earned a reputation for being high quality, and here's a breakdown of why:

Top Tier Certification: This is a key differentiator. The EPA sets minimum standards for gasoline, but Top Tier goes beyond that. By using Top Tier certified gas, you get:

• More Detergents: These detergents act like little engine cleaners, helping to prevent buildup on valves and injectors. This can lead to smoother running, potentially better fuel economy, and reduced emissions [1].
• Industry Collaboration: Top Tier is backed by major automakers like BMW, General Motors, and Honda. This means the detergent package is specifically formulated to benefit a wide range of vehicles [2].

Costco's Specifics: Costco goes above and beyond even the Top Tier requirements:

• Five Times the Detergents: Kirkland Signature™ Gasoline boasts five times the amount of detergents mandated by the EPA [1]. This extra cleaning power could be particularly beneficial for vehicles driven in stop-and-go traffic or used for short trips, which can lead to increased deposit buildup.

Additional Considerations:

• Base Gasoline: While the detergent package is a major factor, the underlying gasoline itself likely comes from the same refineries as other stations. It's the specific detergent blend that sets Costco apart
• Fresh Inventory: Costco's high gas turnover rate means you're less likely to encounter gasoline that's been sitting in storage tanks for extended periods. This can be important because gasoline can degrade over time, potentially losing some performance benefits.

The Bottom Line.... Costco gasoline is a strong choice for most vehicles. It meets Top Tier standards and includes an extra dose of detergents from the Kirkland Signature trademark formulation. This can lead to a cleaner engine, potentially smoother operation, and potentially better fuel economy in the long run.

Further Exploration:
If you'd like to delve deeper, here are some resources:
[1] Costco's Fuel Promise: https://www.costco.com/fuel-promise.html
[2] Top Tier Gasoline Retailers: https://www.toptiergas.com/

[Madsen203]

Originally Posted by BMW5and7

Costco gasoline has earned a reputation for being high quality, and here's a breakdown of why:

Top Tier Certification: This is a key differentiator. The EPA sets minimum standards for gasoline, but Top Tier goes beyond that. By using Top Tier certified gas, you get:

More Detergents: These detergents act like little engine cleaners, helping to prevent buildup on valves and injectors. This can lead to smoother running, potentially better fuel economy, and reduced emissions [1].
Industry Collaboration: Top Tier is backed by major automakers like BMW, General Motors, and Honda. This means the detergent package is specifically formulated to benefit a wide range of vehicles [2].


Costco's Specifics: Costco goes above and beyond even the Top Tier requirements:

Five Times the Detergents: Kirkland Signature™ Gasoline boasts five times the amount of detergents mandated by the EPA [1]. This extra cleaning power could be particularly beneficial for vehicles driven in stop-and-go traffic or used for short trips, which can lead to increased deposit buildup.


Additional Considerations:[LIST][*]Base Gasoline: While the detergent package is a major factor, the underlying gasoline itself likely comes from the same refineries as other stations. It's the specific detergent blend that sets Costco apart[*]Fresh Inventory: Costco's high gas turnover rate means you're less likely to encounter gasoline that's been sitting in storage tanks for extended periods. This can be important because gasoline can degrade over time, [...]

Our local Costco removed diesel from the pump. Not quite sure why. Thankfully I don’t have a diesel any longer.