Found this on a TDI site...
***Cetane levels by fuel company. To ensure accuracy if you have a level to add to the list please forward an email from a corporate office to me, and I will add it to the list. Please bear in mind that the current minimum from refiners in North America is 40. Depending on the quality of the oil used as well as refining processes you'll find 40-42 from refiners in the US and Canada. Anything above that has to do with specific companies additive packages. When companies give a minimum value then it will be listed as a single number. When a company gives a range of numbers bear in mind that more often than not you'll probably find the lower number rather than the higher number. If 40 is listed then it generally means that fuel is bought as is from the refiner--if someone messes up and doesn't put in enough additive at the refinery then that can cause major problems for your fuel system. It's recommended therefore that if you get the inexpensive fuel with low cetane you use a cetane booster (PowerService, Redline 85+ or Stanadyne are all great choices), or run a little biodiesel in the tank. If something higher than 42 is listed then the retailer adds their own additive package in addition to the standard refinery additive package. Generally speaking as long as 49 or higher is listed you do not need to worry about adding any additives yourself.
BP (Amoco branded), 51;
Chevron, 49; or 51 with Techron D labels in select markets
ConocoPhillips through the 76 stations (California) 47-53
BP (Powerblend 47, otherwise 40-42)
Sunoco Gold, 45 (often +1-5) Sunoco regular is usually 40.
Holiday Stations, 40-43
HESS, 40-42, can be up to 45.
Husky, 40 + diesel Max additives raise another 1-3 from there (41-45 max)
Flying J, 40