I can't find the answers anywhere. How much does the Cetane drop in diesel fuel in 6 months, 2-4 points?
How much cetane is to much for a 6.7? I read a CN of 55 is as high as you want to go otherwise it can burn pistons and cause knocking. This was stated for mechanical diesels, and I don't know if I believe it.
If I run premium diesel with a CN of 60 and add Redline 85plus for lubricity, it also boosts CN 3-7 points.
Will a CN of 63-67 hurt a 6.7?
Will I loose 2-4 points in 6 months?
​​​​​​Dustin
edit: found the answer to one question. The renewable diesel has a CN of 70 or greater in California. They run 6.7 powerstrokes there just fine. So it's safe to use atleast a CN of 70.
How much does CN drop in fuel over 6 months?

 

Too many variables to say. The only folks that could give you an educated answer would be the ones who make it. We could “if” it all day long in terms of type of diesel, what state you are in, how it was stored before you purchased it, how you store it. Local environmental factors that could reduce it along with even adding fuel additives all play a part. I do know that I have put fuel in a truck, deployed for a year and when I returned, it fired right up and never had an issue. No idea how many years it can sit. Some may sit for years while others may turn into an algae farm in a few months.

 

I have tried a local fuel source that sells a premium diesel supposed to have a higher cetane. I didn't notice any significant improvements. Adding my fuel additive I can easily see a MPG difference.

 

Cetane only comes into play on a cold engine. It doesn't work like Octane does, slowing the burn, but increasing its combustivness (if thats even a word, if not, I just made it up) so that it ignites faster when cold. Higher Cetane might help improve MPG, but it has a quick drop off which is why you see 55 as a cut off. More is not beneficial to the combustion cycle. IOW you wont gain anything running 70 Cetane than you will 55 Cetane, but you gain a LOT running 55 Cetane over 40 Cetane. Diesel doesn't vaporize like gasoline does, and provided there are good algeacides, and other additives to preserve the fuel, the Cetane levels wont diminish over time.

 

As long as I won't damage the ol' 6.7 using a CN 60-63.
Texas has a CN of 48. If I add a lubricity additive that takes it past a CN of 55, it won't crack a piston etc, I will see if it likes it. It may only take it up to 58-60. I'm saying a CN of 63 as the highest level.
edir: straight from Ford...im good to go.

 

I used to run BP Supreme in my 2001 VW TDI. I noticed easier starts & low smoke on start up, quieter idle, and 6% fuel increase. I uded to track every fill up for taxes. My observation in 77,000 miles.

 

Something to note - Cetane is, in far too simple turns, reverse of Octane. This is an over-simplification as it isn't DIRECTLY reversed, but basically the higher the octane rating of a liquid, the lower its cetane rating. So a fuel with a high octane rating is GREAT for gas-powered cars, but terrible for diesels. Conversely a higher Cetane rating is good for diesels, but will cause gas-powered cars issues.

Just throwing a little scientific information out there, as to WHY you don't want to go under around 50 Cetane in your diesel.

 

I've not seen any premium diesel pumps for years in the KY region. When I used high cetane premium diesel with an additive in my tuned '02 Jetta TDI, I would see 2 to 3 mpg improvement and it felt stronger. I've not noticed diddly squat in either '20 or '22 Superduty 6.7L regardless of where I bought fuel, used my stored fuel or added treatment. I'm presently burning up my winter storage fuels, both gas and diesel at about 10 gallons per fresh tank with additive. Now that the political climate has changed, I'll only store two, five-gallon jugs of each versus ten.

 

Probably around the 50 mark for their Supreme. Everything you mentioned is the benefit of higher Cetane. The thing to keep in mind is after 60 it drops off dramatically and will hurt the engine and economy. Run 40 Octane in a gas engine and things go BOOM. 60 Cetane is on par with low Octane. You don't want the fuel igniting well before it needs to.

 

in the NY/NJ area all the pump diesel is 40.

 

That document from Ford says that's not good.
I would use a heavy dose of Optilube xpd.
the RL 85plus will boost Cetane 3-7 points per bottle description. It works great for Texas diesel but not the gutter swill that you guys are blessed with. I run RL at 6 Oz per 10 gallons of diesel since the truck made it a fuel station with 42 miles on the odometer.

 

I'm at 77k and so far no CP4 disaster. Here in KY 40 Cetane is commonplace though once upon a time I used 52 Cetane "Premium Diesel" at certain truck stops. I don't see Cetane posted on pumps here anymore and some even have an 10% ethanol warning sticker applied. I'm not kidding. Welcome to KY! 😆