Gas Talk (2 Viewers)

[firetruck41]

I use the cheap stuff, 87 octane around here, have in all my vehicles ('cept the BMW which requires 90) with nary a fuel problem yet. All the fuel has to pass the same standard and I believe all now have detergents in them. Also I believe the US uses RON (Research Octane Number?) octane numbers, other countries/continents may use different standards.

 

[cary]

[quote author=IdahoDoug link=board=2;threadid=4623;start=msg35081#msg35081 date=1061880836]
Anyone care to make a bet that the BMWs, Mercedes, and Audis of the world also require premium fuel for the same reasons - not really for performance??

IdahoDoug
[/quote]

I'll bet you. 3 BMW's, from the 70's through 90's. All ping like mad on anything except super. Something about 10:1 compression and highly tuned motors .

Re: Independent Fuel Stations. I live in an area where there are several refiners, used to be friends with a chemical engineer for Chevron, and also represent a large independent fuel distributor. All gas is refined at the same refineries and the same methods. In fact you will find Shell trucks filling at chevron refineries and vice versa. So what is the difference? The additive packages. The specialized packages for each manufacture used to be dumped in the trucks after they were fueled, now they are put in by injection when the truck is being filled. Even independents are required to meet minimum additive package specs. My experience is different cars do differently with different fuels. My wifes BMW works best with Union 76 Supreme. My Pathfinder runs the same no matter what is in it.

The thing to watch out for with any station is slow business. The longer the fuel sits in the tanks, the more crap it absorbs (water, particles, etc.). I love Costco gas, cheap and they fill their tanks 3 times a day.

Cary

 

[Pskhaat]

[quote author=Jonathan_Ferguson link=board=2;threadid=4623;start=msg35064#msg35064 date=1061878308]
Why do you lot call Petrol Gas. ??? ... Petrol Octane ratings in Australia:
[/quote]

Gas = short for Gasoline, syn. Petrol.

I believe the US uses an average of two different ratings and thus ours appear `artificially' lower than international ratings. Please correct me if I'm wrong as I often am, but I believe AU uses the ``research rating'' as the sole numerical designator while the States uses the (R+M)/2 rating, average between Research and Motor Octane ratings.

 

[GXO]

My 3FE doesn't click and clack as much with normal advance with "Plus" gasoline.

Atlanta = 1.60-1.65 for plus right now.

 

[IdahoDoug]

Cary,

Interesting that these engines pinged badly on regular gas - particularly the 90s Bimmer. Generally, modern engines will ping briefly, then the knock sensors do their job and retard timing a bit at a time until it goes away. These days, if you have a continuous ping problem then there's likely an issue with the engine electronics or the cylinders have enough deposits that a) the actual compression ratio is up, and/or 2) the thermal mass of the deposits is enough that ping still occurs even at the limit of the engine's correction range. These deposits generally come from an engine in a poor state of tune, or continous use of poor quality gas.

I got the same info you did from the guy who worked at the Chevron plant on the coast south of LAX regarding sharing of gas. If one refiner brand ran short of a particular grade, they all had an agreement to provide cover. And it jibes with the additives being a major differentiator as he mentioned. However, he felt there was a significant difference between the generic brands that took whatever they found on a price basis in that they met only the minimum standards. The major brands, on the other hand, went well beyond this so they could make claims like you're seeing with Chevron (trucked to Detroit so the Big 3 can use it for EPA certification) and Shell (provides higher MPG than other brands). They spend big bucks trying to develop brand equity, and with that much on the line, it would shock me (and the Federal Trade Comission, incidentally) if there were not material differences.

IdahoDoug

 

[cary]

On the 90s BMW its a trace ping, usually during shifting. No continuious ping. I think they set the timing way advanced and then let the knock sensors ratched it back. On the 80's BMW is a combination of an over agressive distributor curve from 2200-2700, which was cured by recurving the distributor to limit advance.

Concerning the additives, there are differences, but it seems to vary from car to car if they make a difference.


Cary