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diesel discussion or gas Empty Re: diesel discussion or gas

Post by dean Fri Feb 02, 2018 8:55 am

Update re Mexican Diesel Fuel

Update Regarding Diesel Fuel in Mexico - September 27, 2017

The Mexico Snowbird Season for 2017/18 is fast approaching, so here is an update regarding sulfur levels in Mexican diesel fuel and the potential for negative impacts on late model diesels. Please note that I am not a Pemex employee, so I can not guarantee that information provided by Pemex about the availability of ULSD is completely reliable, but lab testing of some random fuel samples, and data from diesel owners driving in Mexico, does appear to confirm the latest Pemex information.

Several things have become abundantly clear over the 10+ years since I first began researching this topic and started collecting data from owners of a wide range of diesel powered vehicles:

All diesels up to and including the 2010 model year, irrespective of manufacturer or vehicle type, have no significant problems from the use of higher sulfur Mexican diesel fuel (LSD). The most noticeable “symptom”, only apparent on 2007.5 through 2010 model years, MIGHT be occasional blue smokey exhaust during regeneration cycles. (Regeneration cycles burn soot out of the Diesel Particulate Filter (DPF) from time to time, and blue smoke can occur when sulfur deposits are mixed with the soot). The majority of owners though will not even see blue smokey regenerations, so will be unaware whether or not their vehicles are burning Mexican diesel.
IN SUMMARY: If you own a diesel vehicle of any model year prior to 2011 you can use Mexican diesel fuel without taking any special precautions.

There is a POTENTIAL for 2011 and later diesel vehicles, the ones that use Diesel Exhaust Fluid (DEF), to experience problems while using Mexican LSD. (Dodge RAMs of 2013 and later model years fall into this category.

Within this group:

I have never received a report of any Class A diesel pusher motorhome having any type of sulfur-in-fuel related problem. This is probably because these vehicles are very heavy, which keeps exhaust gas temperatures elevated, discouraging sulfur compounds from settling out in the exhaust/emissions system. In addition, their exhaust systems are relatively short, so they heat up quickly and stay hot, again discouraging the deposit of sulfur compounds that could interfere with the functioning of the emissions system.
IN SUMMARY: Based on all of the data available at this time, Class A diesel pushers have no negative reactions to the use of Mexican LSD

Sprinters are a very large sub-group of motorhomes that are commonly seen in Mexico. They are relatively heavy for their size, so their exhaust/emissions systems stay hot, which discourages sulfur deposits. However, I have two verified reports of post-2010 Sprinters going in to modes where the number of starts is being restricted, with warnings of a shutdown after those starts have been used. In both cases though the vehicles “healed” themselves, presumably after a regeneration cycle burned soot and sulfur out of the exhaust/emissions system.

Based on discussions with the owners of those Sprinters, the evidence suggests that Sprinters will not typically have any issues using Mexican LSD unless the vehicle is used for numerous short trips for shopping, restaurant visits, etc after reaching a winter destination. These short trips do not fully heat the exhaust system, which allows sulfur compounds to collect in the Selective Catalytic Reducer (SCR).
IN SUMMARY: Sprinters very rarely experience serious issues with Mexican LSD, and probably only when the vehicle is used for frequent short trips that do not fully heat the exhaust system. Owners planning to use their Sprinters for local transport once they reach their final destination should try to carry extra ULSD and use a 50/50 mixture with Mexican LSD after reaching the final destination. A 50/50 mixture of ULSD with Mexican LSD has been shown to cause no sulfur related issues across a wide range of vehicle types.

Dodge RAM pickups have been the least likely diesel pickups to experience any issues with Mexican diesel fuel (LSD). The most frequently reported issue has been excessive consumption of DEF in 2013 and later models as the emissions system injects more and more DEF to compensate for the sulfur contamination of the Selective Catalytic Reducer (SCR) between regenerations.

There is, however, some uncertainty going forward because Dodge has apparently recently negotiated a settlement with the EPA over allegations of improper reporting/monitoring of emissions. It is my understanding that Dodge has agreed to correct the “problem” by reprogramming trucks during normal service visits to dealerships. What is not yet known is how the reprogrammed trucks will react to the presence of sulfur in the fuel, so Dodge owners need to be aware that there is a potential for new fuel-related problems.
IN SUMMARY: Dodge RAMS have generally been symptom free while using Mexican LSD but there is a new potential for issues because of emissions programming updates by Dodge. It may be wise for 2013 and later Dodge owners to obtain a tuner, such as the one made by Edge Products, that can force a regeneration cycle to burn sulfur out of the system. A regeneration should then be triggered if any emissions related warnings are displayed.

Ford diesels generally have not exhibited any issues while using Mexican LSD, but I have three verified cases of emissions related COMPLETE SHUT DOWNS after the vehicles were used locally in Mexico for extended periods on Mexican LSD after arriving at a winter destination.
IN SUMMARY: Ford diesels are usually symptom free while using Mexican LSD but there is a potential for issues if the vehicle is driven on short trips on Mexican LSD once the winter destination has been reached. It would be wise for 2011 and later Ford owners to obtain a tuner, such as the one made by Edge Products, that can force a regeneration cycle to burn sulfur out of the system. A regeneration should then be triggered if any emissions related warnings are displayed.

Duramax powered diesels are the most sensitive vehicles to sulfur in Mexican fuel. They often enter speed limitation modes, and can end up in limp mode (5mph) if special precautions are not taken. (Almost as if Duramax is OVER-reporting emissions compared to other diesels). Owners of 2011 and later Duramax diesels should contact me at if they are planning to travel in to Mexico so that I can make them aware of special precautions that need to be taken. Unfortunately, as of the time of writing, I have not become aware of any tuners available at the retail level that can trigger regenerations on Duramax diesels.


It is NOT POSSIBLE to determine whether fuel is ULSD or LSD by looking at it or sniffing it. The ONLY way to make a reliable determination is with a laboratory test. I have personally collected and run lab tests on samples of fuel from Mexico so I know this is true. If someone says he or she can identify the fuel type without a lab test you need to be skeptical.

The Mexican Government has set the end of 2018 as the cutoff date for Pemex to supply ULSD at every station in Mexico. If Pemex can not upgrade it's own refineries by then, it has to export the fuel produced by those refineries and import ULSD for domestic use. At this stage it appears that 3 of Pemex's refineries have already been upgraded or the upgrades are close to completion, and more are currently being worked on. As a result of the already completed upgrades, ULSD is becoming more readily available and there are now large areas and corridors where ULSD is standard.
NOTE: It is commonly the case that a station will be pumping ULSD without the knowledge of the attendants, and there will not be any label to indicate that the fuel is ULSD (UBA). Do NOT trust any claims by station attendants that they have, or have not, got ULSD (UBA) at the pumps unless they can show you the fuel manifest– they typically have NO IDEA where their fuel originates.

A contact at Pemex recently sent me a copy of the official Pemex list of stations already carrying ULSD. The list is arranged by state and then city or town within the state. I can provide that list to owners of vehicles which may be sensitive to sulfur in the fuel, specifically Duramax owners.

There is reliable evidence that there is presently ULSD at every Pemex in the Northern Baja, down to and including Jesus Maria, about 38 kms north of the border with the Southern Baja. In additon, all stations in the Yucatan are listed as having ULSD, and the main corridors running from the US Border to Mexico City are mostly stocked with ULSD.

I have received recent reports from travellers who say they have seen Gulf and Esso stations now open in Mexico, so the marketplace is presently undergoing a major transformation. As a result of these changes, I am convinced that Mexico will indeed fully convert to ULSD by the end of 2018.

Ted (Ed) White
September 2017

Here's the latest update from Ted White regarding the availability of ULSD on the Baja.

On Tuesday Jan 16/17 I received the results from lab testing of a sample of diesel fuel I collected from the main Pemex station at Los Barriles, in the Southern Baja, about one hour north of San Jose del Cabo.

I collected the sample in late November because there had been ZERO reports of sulfur-in-fuel related issues up until that point this winter season, and my own truck, a 2016 GMC Sierra Duramax had also not experienced any sulfur-in-fuel related symptoms. In past years, by the end of November, I would have needed to force at least 2 regenerations to burn sulfur out of the emissions system, and there would have been lots of sulfur-in-fuel problems in Cabo, La Paz, La Ventana, Mulege, and Loreto.

Five weeks have passed while I have been waiting for the lab results, because the sample had to be transported to a lab in the USA. During these five weeks of waiting there have still been NO instances of sulfur-in-fuel related issues reported to me in the Southern Baja, and my own truck has not required a single forced regen since my arrival at the end of October.

The anecdotal evidence has been suggesting that the fuel in the Southern Baja is now ULSD, and now the lab test has confirmed it. The sample tested at 6.3ppm, which is significantly lower than the 15ppm required to meet ULSD specifications.

I have tried to get official confirmation that the desulfuring upgrade to the refinery supplying this area has been completed but nobody at Pemex will confirm or deny that the upgrade has been done. However, the very low levels of sulfur mean that the fuel came from a very modern desulfuring facility.

At this point I feel confident that there is enough evidence to declare that the diesel fuel in the Southern Baja is now ULSD.

In other words, all of the diesel fuel on the Baja, from top to bottom, is presently ULSD. There are no guarantees in life, but it appears that Pemex has completed the conversion from LSD to ULSD in this area.


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Post by dean Sun Dec 04, 2016 8:14 pm

bpe wrote:Re: Mexican Diesel Fuel Question in the BPE

For more than 8 years I have been collecting data on the behavior of late model diesels while using Mexican higher sulfur diesel fuel (LSD). My knowledge on this subject is referenced in many diesel forums on the net, as well as by RV caravan trip operators.

The higher sulfur levels found in Mexican diesel do NOT harm the engines in late model diesels. Problems, if they occur, happen in the EMISSIONS system which forms part of the exhaust line in modern diesels.

Serious issues with the sulfur levels in Mexican fuel occur only with SOME, NOT ALL, 2011 and later model years – the ones that use Diesel Exhaust Fluid (DEF). Specifically it is the Selective Catalytic Reducer (SCR), which uses the DEF to reduce oxides of Nitrogen in the exhaust (NOX), that is sensitive to temporary sulfur poisoning by the higher sulfur levels in Mexican diesel.

Vehicles with model years earlier than 2011 do not experience any significant symptoms while using Mexican diesel fuel. One thing that MIGHT be noticed though, while driving at slower speeds when a regeneration cycle is happening, is blue smokey exhaust. The blue color is caused by sulfur compounds burning out of the soot filter (DPF) during regeneration cycles.

Generally speaking, 2011 and later Dodge and Ford diesels tend to have relatively minor reactions to Mexican diesel, while GM Duramax powered pickup emission systems are VERY sensitive to temporary sulfur poisoning and WILL need management to avoid going in to limp mode (5mph). Anyone planning to bring a 2011 or later Duramax powered pickup to Mexico should contact me for information about their specific model year and how to manage things while in Mexico.

In terms of the fuel on the Baja, over the past 18 months I have personally collected multiple fuel samples from Pemex stations at Los Pinos, El Rosario, and Jesus Maria and have had those samples analyzed at a lab in the USA. All of the samples were ULSD from the USA or Japan, which is consistent with Pemex’s internal documentation that indicates all of the diesel in the Northern Baja down to, and including, Jesus Maria is ULSD distributed out of the Pemex tank farm near Ensenada. Pemex does not produce enough diesel for it’s domestic needs so it imports some diesel from the USA and Japan and has chosen to stock the Ensenada tank farm with that product.

All of the diesel fuel in the Southern Baja, plus at the one station just north of the border with the Southern Baja, carry Mexican diesel distributed out of La Paz.

I am happy for late model diesel powered vehicle owners to contact me, Ted White, with questions about their specific vehicle at


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Post by dean Fri Oct 07, 2016 8:25 pm

check on gas stations


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Post by dean Mon May 04, 2015 9:40 am

how they rip you off at the stations.


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Post by dean Tue Oct 01, 2013 10:28 pm


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Post by dean Tue Oct 01, 2013 3:53 pm

Today is the last day of summer, and fairly soon a bunch of "Snowbirds" will start heading for their winter destinations, including Mexico.

I've posted a ton of information about using Mexican diesel since 2007, but I like to give an update at the start of every winter season.

For those with an interest, see the text pasted below regarding the effects of sulfur in Mexican diesel fuel on the DPF and SCR of our trucks. 


This informational article summarizes the latest available data regarding the effects of sulfur in Mexican diesel fuel on pickup trucks from the 2007.5 model year through 2014. It is based partly on “real-world” experiences with Mexican diesel fuel, shared with the author by Snowbird pickup truck owners over a 6 year period, but also references the scientific knowledge base that has been built up through emissions system research, and laboratory testing by manufacturers of pickup trucks. Nothing contained herein is to be interpreted as an endorsement or encouragement by the author for owners of 2007.5 and later pickup trucks to drive them into Mexico. The article is written in the interests of information sharing. How you choose to use the information is your own responsibility.

For those who are not yet familiar with this topic, Mexican diesel fuel contains higher levels of sulfur than is mandated in the USA and Canada. The ultra low sulfur fuel in Canada and the USA contains no more than 15 parts per million of sulfur, while Mexican diesel can contain up to 500 ppm. As a result, there is a potential while driving in Mexico for “sulfur poisoning” of emissions system components to occur in pickup trucks which have diesel particulate filters (DPF) and selective catalytic reducers (SCR) included in their exhaust systems. DPFs were introduced in the 2007.5 timeframe, and SCRs were added in the 2011 model year.


Despite the potential for emissions system problems, there is some good news, because, consistent with laboratory test results prior to 2007, all 2007.5 through 2010 model year diesels, whether Ford, GM, or Dodge, are continuing to tolerate well the higher sulfur Mexican diesel. While there are minor issues, like the occasional emission of blue smoke in the exhaust during a regeneration cycle, (i.e. When soot is being burned out of the DPF), these occurrences are temporary and rare. All of the testing prior to release of the DPF equipped pickups indicated that there would be no permanent degradation of the emissions system, as long as higher sulfur fuels were not used for more than 40,000 continuous miles. The real-world field evidence certainly appears to be supporting those predictions at this point in time.

For the 2011 and 2012 model years, some owners have been seeing Diesel Exhaust Fluid (DEF) warnings from time to time, but in all of the cases made known to me, the warning messages have cleared following a 15 minute high speed run, OR during subsequent heavy trailer towing, OR after the next regeneration. All three situations raise exhaust gas temperatures high enough (sometimes above 740 degrees C at the SCR) to purge sulfur compounds from the system. 

The DEF warnings, if they occur, only seem to happen after a fifth wheel or other heavy trailer has been disconnected, and the truck has been driven around locally in Mexico for several weeks. The lower exhaust temperatures, when there is no heavy load to pull, permit the gradual build up of sulfur compounds until the efficiency of the emissions system is reduced and an error code is triggered. There is actually nothing wrong with the Diesel Exhaust Fluid, even though that is the message displayed. It is simply a case of the engine computer interpreting higher than specified NOX (oxides of nitrogen) in the exhaust as evidence that the DEF is not doing its job.

Unfortunately, the 2013 model year appears to have brought with it a bit of a complication, because, it seems, the Environmental Protection Agency made changes to the requirements for monitoring NOX (oxides of nitrogen) in the exhaust for 2013 and beyond. Monitoring has to be more frequent than was the case for earlier models, and NOX reduction must remain within a tighter tolerance level. In addition, regenerations are less frequent because less soot is being produced due to less exhaust gas recirculation in some of the 2013s. As a result of the delayed regenerations and tighter NOX monitoring, 2013 and later model year diesel pickups appear to be more likely to register fault codes while in Mexico, and the process required to clear the codes is more complex.

Also for 2013 and later model years, some owners have noticed that the distance which can be travelled after a DEF fault is triggered, and before “limp mode” (maximum speed 4mph) is initiated, gets accelerated with time. This means that the available non-limp-mode miles disappear more quickly than warranted by the distance travelled. This in turn can create a lot of stress, because it is a very upsetting experience to see a message on the dash that your truck will be in limp mode in a few hundred miles or less. 

The key to clearing the fault situation for 2013s, and likely also for later model years, if the fault situation even occurs, is to get the truck to do a regeneration. This is because the regeneration process burns the sulfur from the SCR and returns the NOX processing part of the emissions system to normal operation. Once the emissions system is able to again properly reduce NOX levels, the engine computer stops thinking that there is a problem with the DEF.


Unfortunately, there is no direct method an owner can use to force a regeneration, but feedback from owners in Mexico over the 2012/2013 winter season resulted in development of what appears to be a very practical indirect method. Apparently, EPA regulations require regenerations to occur more frequently, approximately twice as often, if there is a problem with the DPF pressure sensors which measure soot load in the DPF. In other words, disconnecting the DPF pressure sensors can force a regeneration, provided that more than half the normal distance between regenerations has already been travelled. I have personally seen this procedure used on more than one Duramax powered 2013, and it DOES work.

As mentioned in the previous paragraph, how soon the induced regeneration will be triggered depends on what distance has been travelled since the last regeneration. The theory is, if more than half the normal distance between regenerations has already been travelled, the driver will immediately see a message advising that a regeneration (filter cleaning) has started and to keep driving until it is finished, up to 30 minutes, at highway speed. 

If half the normal distance between regenerations has not yet been travelled, it could be anything up to a couple of hundred miles before a regeneration is triggered. Odds are though, for excess sulfur buildup to have occurred in the SCR, and a fault condition to have been triggered, it is very likely that more than half the normal distance since the last regeneration has already been travelled.

Bottom line is, knowing how to unplug electrical power to the DPF pressure sensors on 2013 and later model years will usually allow an owner to trigger a regeneration, which in turn purges the SCR of sulfur compounds, and clears the DEF warning. 


Hopefully, before too many more years have passed, Pemex will refit its refineries to produce ulsd diesel, and this annual complication for many Mexican snowbirds will be eliminated for good. ULSD is already available at most Mexican border towns and cities, and in some larger non-border cities, but the higher sulfur fuel is still widely distributed throughout Mexico.

While we wait for Pemex to make changes, anyone needing more specific information, or with a personal experience to share, can contact me directly at Please note that there is no information available yet for the latest model Dodge pickups, because the 2014 model year is the first year for Dodge using DEF (Diesel Exhaust Fluid). As a result, there is no real-world field experience to draw upon, and I would welcome input to help improve the knowledge base for all owners.

Irrespective of the manufacturer of your pickup, if it requires Diesel Exhaust Fluid, be sure to take LOTS with you into Mexico. I recommend at least 5 gallons, because the only confirmed source in Mexico at this time is Napa Auto Parts, which will special order DEF from the USA at around twice the normal price.

Ted W
September 22, 2013 


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