Actual Cetane Ratings

Keith Browning · May 9, 2010

I am doing research for an article and I am having difficulty finding anything resembling a study or report on actual cetane numbers of fuel tested at the pumps or in samples that were analyzed. I have found plenty of documentation that shows that North American fuel has a generally lower cetane rating than that of fuel found in Europe for example. I see claims that North American diesel should be from 45 CN to 55 CN but the minimum requirement is 40 CN. We know there is no accurate in-field test so analyzing must be done by laboratories. My FSE commented once that fuel samples often tested in the upper 30'S which is piss poor.

Any ideas on reliable information sources?

Jim Warman · May 9, 2010

This probably isn't what you were after, but it's still a pretty good read. I didn't realize that CN and CI we so different.

I'm not sure about other areas, but here in northern Alberta, diesel is, to a point, offered as seasonally adjusted fuel. When I managed an Esso Petroleum bulk fuel station back in the mid 80s, we could order P40 fuel beginning in late fall. The reduction in power was the first thing an operator would notice due to the reduced cetane number of the fuel.. but the fuel wouldn't gel or "wax off" in our cold winter temps.

FWIW, I think that P40 was actually in that nebulous "almost kerosene" range.

From some of the horror stories seen on the monkey house, I'm almost certain that CN isn't given nearly as much importance as octane ratings when it comes to pump islands.

Suggestion... for input for your article, you might, perhaps, contact some of the major suppliers (Exxon, Esso Petroleum Canada, etc) directly?

Bruce Amacker · May 9, 2010

I used to run diesel fuel samples regularly when I had the shop using Napa/Wix PN 4077 Oil Analysis kit, but they removed diesel fuel from the allowable fluids to be sampled and put it in a different (and much more expensive) kit. it used to be $13-14 and now it's about $80 for a basic analysis that does not include lubricity.

Anyway, I regularly got cetane samples in the mid to upper 30's and one was 34.

Have you (or anyone) used CTC Analytical Services in Cleveland? The local FMC training center has some kind of connection as Ford supplied them with fuel analysis kits from CTC. 800-726-5400, I'll get more info next week.

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Keith Browning · May 9, 2010

Jim that document is similar to a lot of what you will find when "Googling" the subject using different words. There is also a lot of industry lingo and chemistry that I know makes no sense to me, nor should it. To me it seems "logical" that a cetane rating should be guaranteed and posted on the pumps. They do it for gasoline so... ?

Bruce, I believe that testing fuel samples taken directly from the pumps and from vehicle tanks is indeed what I am looking for as what ends up in the consumers fuel tanks is the bottom line. I am a little surprised that I cant find any kind of aggregate testing data on a large scale. Mostly what you see published is furnished by the oil companies but again, where the fuel starts out and where it ends is likely a different story I contacted a couple "friends" to see if there is any Ford information on this. I KNOW they do fuel testing and research.

From what I am reading and things I have heard over the years I guesstimate the average is going to be from 38-CN to 42-CN but that is simply not good enough. At any rate, if the average still meets 45-CN then I would think that using fuel additives to target 50-CN is still good advice. I also have read in several places that improvements in performance level off around 55-CN.

The bottom line: I have heard from more than a handful of people from Ford Motor Company that have stated that the quality of diesel fuel in North America is poor. All I want is a simple explanation or data to support it. I agree that fuel quality is probably the largest factor contributing to performance issues and carbon related concerns but it is not the only answer.

Jim Warman · May 9, 2010

Well. it is trying to snow right now (big, heavy, slobbering flakes that melt as soon as they hit) so I have been driven indoors... Not that putting up soffit was something I really want to do today and I am a touch under the weather (we've been passing some head cold thing around at work).

This is something I just stumbled across and haven't yet had chance to do any more than skim over it.

Interstingly, on page 27 it states that there is no federal requirement for cetane number nor cetane index. CGSB (Canadian General Standards Board) specifies a minimum cetane number of 40. But here is where it gets murky. Ontario has adopted the CGSB standards... but British Columbia used to adhere to the standard but have rescinded the requirement. Quebec also has a requirement fo a minimum cetane number of 40 but, since they don't really consider themselves part of Canada, they have passed an Order in Council (they will only use Canadian shit when they can profit from it). AFAIK, in all other provinces and territories, without a cetane number requirement, nobody is going to bother testing - and I have yet to see ANY diesel pumps advertising a cetane rating (meaning no oversight from any trade commission).

There is some anecdotal info in THIS thread. Reading similar threads around the internet has me seeing oil companies put a spin on their product. Our fuel exceeds CN 40 but is "usually" closer to CN50 kinda spin doctoring.

I'm reminded of food packages bearing "MAY CONTAIN" warnings... we aren't sure what's in our stuff.. but we think it's better than we think it is...

Keith Browning · May 10, 2010

Now I feel less stupid or at least I am in good company. You are coming to the same conclusion I am based on similar findings.

Cetane · May 11, 2010

Here is a little data courtesy of our friends to the north.

http://www.ec.gc.ca/cleanair-airpur/CAOL/OGEB/fuels/reports/fullreport/fullReport_p4_e.cfm#t4.3

You can also search for the Alliance of Automobile Manufactures North American Fuel Survey or the SGS worldwide fuel survey but you have to buy them, they arent available for free.

LARRY BRUDZYNSKI · June 4, 2010

Keith, For what it's worth.....For every 10 pumps or injectors that come thru my door 8-9 of them are from contaminated fuel, water is the biggest killer and lack of additives are from the rest. This ULSD sucks. The lack of lube/sulphur in the fuel is killing the fuel systems. It's basically been dried out and is causing major wear/scoring issues with the fuel systems. We have seen a great deal of business due to this. The CR systems seem to be the hardest hit for this. We are selling more additives than ever, even in the summer. We are having a hard time keeping enough on hand to meet the demand. End users really need to be educated on this it would save them time and money on costly repairs that really wouldn't be needed if they were using a additive. So far I have found that EZ-Oil works really well. We have sold all the common ones Power Service,Stanadyne and a few others but EZ-Oil seems to be working the best. All around good choice is the Diesel Aid plus Cetane D25-16. All the guys here have been using it in their own trucks and have not had a failure so far(Knock on Wood).