Something to think about

[42pilot]

I built an engine for a friend who spent more than $45,000 in parts just for the engine and the car is probably worth around $85 - $90,000. He bought the best parts he can afford - forged Pauter rods, custom ground and drilled crank, custom ground cams, custom forged pistons, custom... you get the idea.

We are tuning it right now but it is not producing the power we thought, even with all the high-end parts - should be about 650 hp from the 3.6L flat six. He has been driving it for about 4 or 5 months now and it's been getting worse. WTF...

Yesterday, he decides to clean the fuel filter as part of the diagnosis process for low power. Below you can see what he found. I asked where he buys his gas (needs to be high octane because of the power). He told me its from a generic station not too far from his house that sells 100 octane. Unfortunately, the shop does not sell that much fuel and apparently does not clean their filters too often.

The fuel color in the filter was amber-bock.

This will cost my friend all new injectors (about $800), new pressure regulator (about $350), new fuel damper (about $300) and possibly a new fuel pump (about $1200). In addition, we will have to flush the entire system including the tank, all lines (supply and return), fuel rails, etc.

I will bet he will not buy fuel from a low volume, generic station again.

Something to think about

[opasha]

Wow...that's crazy. Thanks for the post. I'm glad I've never bought from low-volume, generic gas stations.

[Snow-Kidney]

Originally Posted by opasha

Wow...that's crazy. Thanks for the post. I'm glad I've never bought from generic gas stations.

Seems like it might be more of a low-volume rather than generic gas station issue.

[opasha]

Originally Posted by Snow-Kidney

Seems like it might be more of a low-volume rather than generic gas station issue.

sorry, that's what i meant to type since that's what he mentioned. corrected it .

[F15GorDe]

My fear with low volume, low cetane diesel when out and about in areas I'm not familiar with.

[artem123]

I purchased gas from generic station few times. If you want i will tell you exactly where it was.I NEVER fueled my cars with anything less then 93. Ones me and my wife drove by this station and filled up our then 6-7 month old Touareg ( back in 2008). We drove about 2-3 miles back home after fueling. Next morning i took other car to go to work and wife took Touareg. She calls me and tells me treg "does not speed up". I rush to look at it and Treg virtually does not go faster then 20-30 mph. I took it to dealer. Manager calls me next day, and tells me that "liquid in my fuel tank has octane number of 68.....". Never again i put a drop of gas in my cars from non branded stations.

[cenix]

What the heck is that crap? Sand or dirt?

[Zipforia]

Originally Posted by artem123

I NEVER fueled my cars with anything less then 93.

Where in US sells 93 octane? Best we have in SoCal is 91.

Z.

[Kzang]

My area has a gas station called Sunoco with 87, 89, 91, 93, 100 octane.
I'm not convinced about the brand of gas station being "Bad" since gas is distributed from the same refinery with different additives, but I feel that the low volume stations might need to be cautioned. But I am not an expert so who knows.

[JOHNBMWM5]

I had an experience (not costly though) with TESCO99 Momentum fuel, I pulled into a filling station on some estate (no names) and filled up............ Feck me what shit, car ran like a Dog.

Never again, I always use "main stream" garages now.

[cenix]

Originally Posted by Zipforia

Where in US sells 93 octane? Best we have in SoCal is 91.

Z.

Everywhere except states like CA, NV, AZ, maybe a few others

[Zipforia]

Originally Posted by cenix

Everywhere except states like CA, NV, AZ, maybe a few others

Damn...now I gotta move.

Z.

[Broadsword]

That's my concern with using AAFES (Army Air Force Exchange Services) gas because I'm not sure of the quality. But I can't complain about paying $2.40/gal for 93 octane.

[r33_RGSport]

Originally Posted by Zipforia

Damn...now I gotta move.

Z.

Are you sure?

Well, I just recently playing around with the E85 mix.
I put a full tank of 91, then after 40 miles of driving I topped it up with E85 for about 2-3 gallons.
It sure improve the power.
Not sure if it do-able without BMS JB4 Stage 2.
I am going to experiment with more percentage mixture.

[mattsnow]

Kzang is right that in many markets all the gas comes from one or a limited number of refineries, the only difference is the additives which really don't do much (they are just a marketing ploy to get you to buy pricier gas). Gas is a highly regulated commodity, with little room for variation. Unless there is fraud, no name stations carry the same gas as the branded stations except for those ineffective additives.

That said, higher volume stations are more likely to have better gas. Gas does undergoes changes with storage, and higher volume stations have less of these problems.

It used to be that there was more variance in the piping and storage at different stations that could affect the quality of the fuel. But environmental laws have come in that have caused all the old stations, with problematic infrastructure, to close. I do look for a station that seems to have well maintained infrastructure, and no way for water to get into their tanks, but i don't know if this is important.

As far as octane goes, 100 is not better than 93. What you need is the minimum octane necessary for the compression ratio of your engine. Any octane rating above what is needed won't get you anything but a lighter wallet. Just follow BMW's recommendation for the minimum octane rating.

Personally, I get almost all my gas at Costco because I am there often enough, the price is the lowest around or nearly the lowest, and the stations do a high volume and seem well maintained.

[42pilot]

Originally Posted by mattsnow

Kzang is right that in many markets all the gas comes from one or a limited number of refineries, the only difference is the additives which really don't do much (they are just a marketing ploy to get you to buy pricier gas). Gas is a highly regulated commodity, with little room for variation. Unless there is fraud, no name stations carry the same gas as the branded stations except for those ineffective additives.

[snip]

Sorry, but I have to call BS to the ineffective additives comment. This is based on building and working on performance motors for over decades, and watching/monitoring the fuels people used - including my own motor. For example, Chevron states they use Techron to keep the system clean. In older fuel injected motors, the injectors were placed before the intake valves (unlike direct injectors used now) which would spray fuel in the intake, covering the intake valve (side benefit - cooled the valve) then into the combustion chamber. The top side of the intake valves, under heavy use such as track or worse, stop and go city traffic, would carbon-up with fuel other than Chevron. Then we started using Techron additive in tanks and found not only the valves were cleaner, but the combustion chambers and piston tops were cleaner. Sea Foam had a similar affect.

At the same time, I would recommend track cars use 100LL aviation fuel for two reasons: lead is a lubricant in fuel (good for pumps, injectors, valves, etc) and 100 octane ensured the fuel burned rather than created an explosion (nearly no chance of detonation in a properly tuned engine) - it was refined better than pump gas. But AvGas is hard to find and nearly impossible to buy because of the lead content. FBO's won't sell it for anything other than recip aircraft. But when cars could use AvGas, the inside of the engines were spotless. And if you feel more power with higher octane fuel, it means it is cleaning the induction system as octane just means the fuel will burn at a very controlled rate - it does not add power. If your motor is really gummed up, you'll also feel the motor run much smoother over time.

Anyway, I've seen the effects of at least one brand of fuel that really works as advertised. And I've seen the effects of what fuel purchased from generic stations do to motors. The irony here is, I don't care what you put in your tank - it's your car. For more irony, I buy diesel fuel from the local Kroger grocery store, but they turn inventory fast.

[mattsnow]

Thanks for your post 42pilot. It got me thinking and doing some research.

My opinion that "all gas is the same" came from some gasoline marketing clients i have had over the years. It seems possible to me now that their statements may have been Alaska-specific (where we used to have two refineries and now have only one refinery for the entire state), and may not be strictly true, even in Alaska, for some high volume retailers who may be able to economically specify a different formulation.

All gasoline contains detergents, as per EPA standards, but some gasolines contain more detergent than others. The chemistry actually turns out to be quite complex, with sulfur and some other minor constituents having a large effect on the performance of different detergent additives. Although complicated, more detergent is generally better than less, especially for the types of engines in our X5s. Chevron's Techroline (Techron) is a polyetheramine (PEA)-type detergent. There are other types of detergents. For instance, I found one study that suggests that PEA detergents are less effective than Mannich-type detergents. So it is possible that it is not just the quantity of detergents but the type of detergents that could affect the performance of a gasoline. I did not find any clear evidence that one detergent is always better than another, or that there is some minimal acceptable amount, or that the additives you can buy at NAPA are any better than those found in gasoline, etc. The whole thing seems very complicated, with various claims and counterclaims, and lots of unsubstantiated anecdotes. I walked away from this thinking that detergents are good and some gasolines may not have as much as is optimal, but that the whole subject is very complicated.

It turns out that some automakers, including BMW, have gotten together to promote a standard called top tier gasoline. Gasoline that meets this standard has more detergents and other characteristics that does indeed make it "better." Google "top tier detergent gasoline" for a list of who markets this better gas. Turns out Costco is one of them.