Pemex Premium availability - and MTBE right now

OK, John wins this one-----can't let that happen too often.

Yeah....those rubber gas cans have a tendency to expand.

So....what is your point, Ralph?

While most cars on the road are indeed designed to run "safely" on regular, your statement that there's "absolutely no benefit" from using premium is - IMHO - inaccurate. Every vehicle is different in how much - or how little - they will benefit from using it though.

The referenced article has its flaws, including no consideration for the change in performance and/or economy due to the spark advance in modern-day ECM systems. Might seem like small stuff, but little things add up.

Running on Regular

Ain't that a fact...

Quote:

Originally posted by BajaNomad Quote: Originally posted by Bajahowodd "The good stuff"? The majority of vehicles on the road are designed to run on regular. Check your vehicle manual. If it says regular, you will get absolutely no benefit from pumping premium. Interesting quote in this article is that putting premium into a car that's designed to run on regular is like throwing quarters into a wishing well. http://www.consumerenergycenter.org/transportation/consumer_... Not quite sure what you are implying here, Jefe. While I wouldn't hang my hat strictly on the term absolutely, given the plus or minus 20 cent a gallon difference, I just think that there are probably way too many folks out there who are throwing money into the wind with the misunderstanding that premium fuel is somehow better. Higher anti-knock octane. But fundamentally not "better". The premium fuel is marketed as being better. It's a lie. As I mentioned, by and large, if your owners manual tells you that your engine runs on regular, you will probably not benefit from buying premium. The oil companies would. While most cars on the road are indeed designed to run "safely" on regular, your statement that there's "absolutely no benefit" from using premium is - IMHO - inaccurate. Every vehicle is different in how much - or how little - they will benefit from using it though. The referenced article has its flaws, including no consideration for the change in performance and/or economy due to the spark advance in modern-day ECM systems. Might seem like small stuff, but little things add up.

Ahhh... but there it is. It's not a lie, it's true. Premium-grade gasoline is (in general) better, higher-quality gasoline. Here's the thing: some vehicles can take better advantage of using premium than others though... and that's where it can get into the "is it worth it" debate - and every vehicle on the road is different.

Mex Reg

Quote:

Originally posted by BajaNomad Quote: Originally posted by Bajahowodd ...there are probably way too many folks out there who are throwing money into the wind with the misunderstanding that premium fuel is somehow better... But fundamentally not "better". The premium fuel is marketed as being better. It's a lie. Ahhh... but there it is. It's not a lie, it's true. Premium-grade gasoline is (in general) better, higher-quality gasoline. Here's the thing: some vehicles can take better advantage of using premium than others though... and that's where it can get into the "is it worth it" debate - and every vehicle on the road is different.

Octane rating is one factor - and generally the factor almost everyone is most concerned with. Funny thing is, you don't even know what octane rating they're using in Mexico. Is it the RON, the MON, or the AKI (R+M/2)? It doesn't say on the pump like it does in the USA (if you look at the yellow sticker in the USA, you'll see the R+M/2 indication - also known as the Anti-Knock Index or AKI - and the AKI is only an average of the RON and MON. RON is more of a non-load rating while MON is more of an under "load" rating - with MON probably being more important to know than RON or AKI).

Regardless, to get higher octane ratings it necessitates blending in a higher percentage of the higher-quality fuel components.

Assuming Mexico follows the ASTM standards for spark-ignition automotive engine fuel ( Reference: http://www.astm.org/Standards/D4814.htm ) - and the "summer"-type blends that would most likely be used throughout much of the year in Baja - the Pemex Premium product most likely has a higher amount of aromatics being used and less cracked stock - or other, cheaper - components.

Aromatics are higher-octane components that cause little or no deposits to form, and have a higher heat of vaporization - which cools the intake charge, and can help reduce the engine's operating temperature. Cruising on a flat stretch of highway the cooling benefit is marginal, but under "load" can be more significant.

"Load" situations can be accelerating out of corners, going up hills, accelerating to pass others, pulling trailers, even just hot weather conditions, etc. There's a lot more of this going on along Hwy 1 in Baja than on I-5 in Southern California IMHO.

With modern day ECM systems having knock sensors that adjust spark advance, the higher octane fuel can also help the engine either maintain or improve the performance it was designed to deliver - especially under "load" situations such as those mentioned. If the knock sensor detects pre-detonation ("knock" or "ping"), it retards the timing, decreases the economy, etc. The ability to maintain or improve the designed performance can lead to better overall fuel economy.

This doesn't even get into the distillation curve of the different fuels. The temperatures at which the fuel burns off can impact the performance and economy experienced.

Just about every vehicle on the road has a different situation and may or may not be able to take advantage of the better fuel components that make the higher octane fuels.

For me, premium in California right now is about 6% higher cost per gallon (in Baja, about 9%). Specifically in my Tacoma I take to Baja (a 2.7L 4-banger), I generally get about 10% (plus or minus) better fuel economy using Premium. It actually appears that (based upon the sample size of about 1800 miles on this trip) the Pemex Premium was slightly more fuel efficient than the Premium I buy in California (generally Chevron, sometimes Shell or Mobil - but never 76 or ARCO).

The detergent in the Pemex is a big question mark too, but using the Premium makes it less of a long-term issue for engine maintenance/repair/etc. They only put detergent in street gas because of the deposits the cheaper fuel components leave. The 0% cracked stock of performance gasoline used in motorsports (think: NASCAR) has no detergent additives, and leaves zero deposits.

What's this mean for the "average Joe"... well - maybe not much. But here's a thought... try a full tank of Premium and see:
A) If fuel mileage improves.
B) If the engine is more responsive when accelerating to pass, pull a hill, or coming out of a corner, etc.
C) If the engine operating temperature is a little lower, especially under load.

If none of the above 3 things seems to be any different or improved, then stick to using regular. Your cost to find this out: probably less than $6 for a 25/gallon (or less) fill-up.

Literally, for everyone YMMV.

I believe I've stated everything above pretty accurately.








[Edited on 1-5-2011 by BajaNomad]

Interesting Read

I'd be curious how many have experienced a "pinging" using Mexican gasoline, and what was the vehicle.

Even running my 1991 Honda fuel injected m/c using regular I had no adverse effects, pinging or reduced power.

Quote:

Originally posted by tripledigitken I'd be curious how many have experienced a "pinging" using Mexican gasoline, and what was the vehicle. Even running my 1991 Honda fuel injected m/c using regular I had no adverse effects, pinging or reduced power.

Chevron Corp and Royal Dutch Shell ?

I presume confusion comes from this:

1997:
- Shell and Texaco merged their western and midwestern USA marketing and refining business into a new venture called Equilon.
- Shell and Star Enterprises (a joint venture of Texaco and Saudi Refining) merged their eastern and southeastern USA marketing and refining business into a new venture called Motiva.

2001:
- Texaco and Chevron merge into ChevronTexaco. Texaco is required (and does) divest itself from the Equilon and Motiva ventures.
- ChevronTexaco licensed the Texaco brand to Equilon and Motiva through June, 2006 (essentially) - which gave Equilon and Motiva time to rebrand their Texaco stations to Shell.