December's Pemex fuel prices

My understanding is Top Tier . . . http://www.toptiergas.com/faqs/ . . . has to do with detergent additives different brands have put in at the refinery. I do not know how this works. I am no expert. But - for example - in the Denver area (as well as other areas) there is one refinery . . . http://www.suncor.com/about-us/refining . . . and all stations get their fuel from there no matter what brand the sign outside says it sold at that station. I think it is possible different brands specify what other stuff they want in the gasoline they sell but the basic stuff is all the same. These different oil companies do not necessarily have their own refineries. In fact few do anymore.

I recently wrote here about Gulf Oil since they were mentioned as being among the companies wanting in to Mexico. Gulf produces nothing these days - they just sell. That is true of many others - just a recognizable brand name that could mean nothing.

And the Top Tier thing is some kind of trademarked designation stations get for using a certain detergent blend. And as Mex says there is no guarantee that once they get the sign on the pump that the detergents are still being added.

I buy junk fuel - don't care what brand it might be - the cheapest I can find - gas or diesel - never had a problem in 55 years of driving - 35 years with diesel. Not saying it can't happen but it hasn't happened to me.

I did once have the sort of problems mentioned here - poor performance and bucking and sputtering - it was the oxygen sensor in the exhaust pipe that determines something about the mix and tells the computer to adjust fuel or firing or something. Seemed like a fuel problem but it was this bad sensor that was not sending the correct message to the control system.

So who knows what is good or bad? I sure don't.