This what Shell had to say about fuel tank contamination and other things. Still no warm feeling about the future;
Hello Jeff,
Here are some bullets points from which you may draw answer to your inquiries.
1- Cetane Number:
In Canada there is a National Standard for Diesel Fuel namely CAN/CGSB-3.517 Automotive Diesel. In the US the spec is ASTM D975 Standard Specification for Diesel Fuel Oils. Both the Canadian & US specs have a minimum Cetane Number requirement is 40.0 as measured in the Cetane Engine Test (ASTM D613).
The reality is that the vast majority of diesel fuel sold in Canada & the US is used in Heavy Duty Diesel engines such as those used in on-road trucks, off-road equipment (tractors, mining equipment, etc), even new technology locomotives require diesel fuel that meets the above specifications. Unfortunately, unlike Europe, the use of diesel by light duty passenger cars is quite a small part of the market.
In Europe the spec used in most countries is EN 590. The minimum Cetane Number spec varies with the expected weather, in most of Europe it is 51.0 min, however if the fuel is used under colder conditions the minimum Cetane Number requirement drops to 49.0 with a -10 deg C cloud point, then 48.0 with a -22 deg C cloud point, then 47.0 with a -28 deg C cloud point, the coldest grade they specify has a -34 deg C cloud point (& a 47.0 minimum Cetane number).
In Canada, even in Southern Ontario the cloud point supplied in winter has to be colder than -24 deg C to match with our expected minimum temperatures. In Western Canada the typical winter diesel fuel meets a -37 deg C cloud point specification. In certain colder areas of Canada a -43 or even -48 deg C cloud point diesel fuel is supplied.
Cetane quality in diesel fuel comes primarily from paraffins (i.e. wax like a candle). The EN 590 spec as described above reflects the reality that in order to meet their colder cloud points the amount of paraffins in the diesel fuel has to be lower and so the Cetane quality is then allowed to be lower. So realistically compared to Canada the European spec drops to 47.0 minimum that limit would only apply in Southern Ontario, parts of the Maritimes, Vancouver & Vancouver Island. The European spec does not address fuels that are used in winter in most of Canada.
This is a similar situation to the use of biodiesel, what may seem to be a great idea in Europe and the US becomes much more difficult in the cold climate that we have in Canada.
Cetane has no impact on the performance of the fuel injection system. It has an impact once the fuel is being combusted. A higher Cetane number will generally result in a faster cold start, lower noise levels after a cold start, less white smoke after a cold start & usually a less noisy idle under all conditions. Once the engine is warmed up then idle noise is the most customer perceivable issue with lower Cetane. EGR plugging is a known issue with VW TDIs, & some suggest that Cetane quality has an impact; I can’t say I have seen any definitive studies that support this contention.
2- Lubricity:
In terms of lubricity this seems to be an issue with the latest technology VW TDI which is why they are so worried about gasoline contamination (as gasoline has inherently poor lubricity).
In Canada all ULSD has to contain a lubricity additive as per the National Standard. I am not aware of any supplier that does not add a lubricity additive to their ULSD in Canada. We specifically did not add a lubricity additive to our V-Power Diesel package as we did not see any need, as ULSD has more than sufficient lubricity as currently supplied in CANADA. Also note that the Standard for lubricity in Canada is more stringent than that in the US Spec (ASTM D975).
If you are still concerned there are aftermarket additives, however as we don’t produce them we have no control over their efficacy or possible side effects.
3- Deliveries to Stations:
When fuel is delivered to a service station a gravity drop approach is used & the flexible lines used are drained dry before they are disconnected from the underground tank. We do put some effort into avoiding contamination of diesel fuel with gasoline as very small levels will cause the flash point (a legal requirement) to decrease & become off spec. Drain dry is also what is used in the trucks that deliver fuel. For small customers with their own storage we do have policies & procedures in place to ensure that fuels are not contaminated by other types of fuels when the delivery truck has a hose reel. Typically theses small trucks will have two hose reels, one for diesel & one for gasoline so as to prevent any cross contamination.
Sorry for the long reading. I thought it is important to supply you with most important factors to be considered.
Please let me know if you need further help.
Kind regards,
José Meilo
Shell Technical - North America
Email:
Shelltechnical-CA@shell.com
Toll Free Tel.: 1-800-661-1771