mdude

Have a question that is not so much about Octane but sourcing of gas:

Would it be a true statement to say all major brands of gas is fine for our cars? Is a 93-Octance from Costco the same as a 93 from, say, Shell or Chevron?

I've been using Costco for years, believing it to not be the highest grade money can buy (at an given octane) but nonetheless good enough for the P-car. True/false?

Ed Hughes

I'm not sure if they have changed, but at some point a couple of years ago, IIRC, Costco gas had no detergent additives, unlike Chevron, Shell, etc.

Steve Weiner-Rennsport Systems

Thats really an excellent question and sadly enough, it depends on what state you live in, whether they run a testing program, and applicable state laws.

Here in Oregon, the state hardly has even a token testing & compliance program so its Laisse Faire for gas wholesalers and retailers. Further, OR laws allow the sale of "end gas"; fuel that's left in the pipelines when they changeover from one product (heating oil, gasoline, diesel) to another and its quality isn't good.

You might wish to investigate & learn what your state's fuel laws are to get an accurate answer to your question.

mdude

Thanks, Steve, for taking the time to reply. I'm in TX.

Further, is pro-longed used of E10 or even E15 fuel (% of ethanol) adverse to 993 engines?

mdude

Costco claims to have 4X the required cleaning agents to gov't requirements. I have no idea what that exactly entails, but take it to mean it has some detergent.

Kika

In short, no. All brands have slightly different additives.

RON is just the octane level that must be met. Think of it this way, different wines may have the same alcohol content, yet taste drastically different, AND have very different qualities.

I was told that Costco sources gas from the low bidder, while the major brands may submit bids, I doubt you are getting Chevron with Techron at Costco prices.

Additionally, Texas Costco may operat differently than the Costcos in other states or regions. I suspect they each have to meet whatever regulations apply for that area, and that is likely different, especially here in CA.

Stuttgart951

I suppose my words do suggest that; yes.

Specific location and winter/summer blends notwithstanding; would it be accurate to state that burning a lower octane fuel from Gas Station X could result in a relatively increased risk of carbon buildup when compared to a burning a higher octane fuel from the same station?

CalvinC4S

Chicken urine and sudafed through a coffee filter will clean that right up. Don't forget to pop your O2 sensors out first and have a couple friends plug the holes with there thumbs. Post 95-

Only 1 friend needed 94-95

But for most cases I would go with premium if you can.

Bonster

I do not agree or disagree, but I once heard that if you run a high enough octane (premium?), it doesn't matter what brand as it will burn clean enough. Not sure about that statement -this thread seemed like a great place to bring it up.

Steve Weiner-Rennsport Systems

My pleasure.

E10 is OK, but E15 is certainly not. Long-term use of E10 simply means that any rubber fuel system component won't last as long as possible and I usually replace such things either by inspection or by how old the car is.

Steve Weiner-Rennsport Systems

Unfortunately, not true.

Octane ratings do not affect the detergent package that oil companies use. Some use more and some use less to save money and boost the net earnings.

Based on my observations, I've found that a regular program of using good fuel additives keeps the injectors cleaner for longer periods as well as controlling soft carbon deposits on the back of the intake valves.

I've had success using LubroMoly Ventil Sauber & Jectron together as well as the large bottles of Techron.

Bonster

Thanks, Steve. I always thought that was a little fishy. I don't have as many options as some areas, but I still never use a "no-name" company. I will be more careful to make sure of those detergents. Think I will start using that additive as well, especially since my cars see a decent amount of track time.

What brands (not station names, but the fuel itself) do you most recommend?

tian647

I'm certainly not Steve but I'll suggest this is a reasonable place to start: <http://www.toptiergas.com/>

Also it is useful to note that most gas formulations are very region specific - there's typically only a single wholesale depot that all the franchise affiliates send their trucks to top off at so you get the same base fuel stock across brands; what differentiates the retailers (and grades) is the proprietary additive package they mix into their unique blends.

Regards,


Christian
'95 Carrera

Bonster

Awesome info, Christian, thanks.

blacksparrow

Agreed.