Macster

Costco gas is 'supermarket' gas and this varies in quality due to the mix of suppliers used to fill the tanks.

Stick with a name brand gas. I prefer Shell in my Porsches (and we can't even get 93 octane here in CA, only 91 octane), although I use Chevron or Union 76 or Philips 66 depending where I am.

Buy from a busy station to ensure you get fresh gasoline.

Avoid filling up if the station is receiving a delivery for fuel from a tanker truck.

I would not use any fuel additive on a regular basis. Techron especially which is really strong in the bottle/concentrated form.

Also, after using it I like to change the oil/filter, because it dilutes the oil.

For both my cars I use a top tier gas and use Techron only every 2 years (if that often) just a few tanks before an emissions test/check. My 02 Boxster just passed CA emissions with pretty good numbers and it has over 255K miles on its engine, fuel injectors, and converters.

The best course of action is to use a good gas to begin with. This keeps the engine's fuel system/chambers free of deposits.

Sincerely,

Macster.

amfp

Amazed that Sunoco did not make the "toptier gas" list.

Domer911

TOP TIER is a ratings game between the majors and the auto manufacturers. Kinda like sweeps week on television. Your government regulates the content of every dispensed gallon in the US. Additives are a point of differentiation upon which the majors rely to lure unwitting consumers to their brands.

I promise, once one of the majors produces a gasoline that gives you better mpgs, is better for the longevity of your vehicle...whatever, you will hear it in the news, instead of in some major fuel supplier's marketing materials.

vexed

I think you meant aloha petroleum. Tesoro was not top tier last time I looked. The trick for Costco gas is to go when the store is closed

ato911

Treat your baby to some 100 octanne. Only $15 a gallon.

mdrums

Would not make any more power....the car is designed to run on 93 any more octane (less volatile fuel) could produce less power.

mdrums

Best advice so far

Skibum

I tried the 100 octane thing for nearly a whole summer.
It doesn't make a difference..

XR4Tim

When I was working at a Audi/Porsche/VW dealer, I pulled the intake off of my Passat W8 (125k miles), and the valves were 100% clean. I only ever ran Shell or Chevron in the car. I have seen many other VWs and Audis with lots of carbon on the valves, and the general concensus was that they used lower-quality fuels.