TWL: Do you ask for low-sulfur diesel?
Last month, I came south from Newport to Chesapeake with Charlie Corbett on
BILLY THE EAGLE, a Krogen 58...real nice boat! He has a pair of Deeres and
noticed that the manual requires less than 0.05% sulfur in the fuel. If you
are not using the low sulfur fuel, the manual says to DOUBLE the frequency
of oil changes...from every 250 hrs to 125. (I checked the latest (since
they dropped the 2-strokes) from Detroit Diesel on my 4-71s and it's less
than 0.05% also.)
So he started asking suppliers for sulfur content info. Most did not know
offhand and has to check. Many had relatively high sulfur content...3 times
more desired. Hard to find low sulfur fuel.
Is anyone asking for low-sulfur fuel? And what are your findings?
Thanks,
Bob
R C Smith Jr
M/V MARY KATHRYN (new name, ex-SUSAN MARIE)
Hatteras 58 LRC
Currently in Annapolis
----- Original Message -----
From: "R C Smith Jr" Bob@Garrett-Smith.com
the manual requires less than 0.05% sulfur in the fuel. If you
are not using the low sulfur fuel, the manual says to DOUBLE the frequency
of oil changes...from every 250 hrs to 125.
So he started asking suppliers for sulfur content info. Most did not know
offhand and has to check. Many had relatively high sulfur content...
Hi Bob,
First, a couple of generic facts about diesel fuel in the U.S.A.
-
Diesel is refined in two "flavors": High Sulfur (HS) which is required to
have no more than 0.5% sulfur content and Low Sulfur (LS) which is required
to have no more than 0.05% sulfur. -
Diesel is sold with one of two tax statuses (stati? statim?): On-Highway
which has state and federal road taxes included in the price (here in
Washington that adds $0.35 or so per gallon) and Off-Highway which doesn't
include those taxes but may be taxed in some other way such as sales tax.
2a. Off Highway fuel is distinguished by a red dye - It is very expensive to
get caught with red fuel in an over-the-road vehicle.
- For environmental reasons it is mandated that only LS fuel be used in
over-the-road applications and in some states, such as California, that
requirement also extends to off highway and marine use as well.
What that means typically is that the fuel available at most fuel docks will
be HS diesel with the red dye. It is, of course, possible to produce LS
product with the dye but, since LS is somewhat more expensive to make,
nobody does it unless they have to.
It's not surprising that most of the docks didn't know the actual sulfur
level of their fuel. That sort of information is not considered important
for day-to-day operation.
As to the service interval question: The difference in oil change frequency,
in this case, is a function of potential TBN depletion. Higher fuel
sulfur levels mean that more combustion acids can be formed which leads to
your TBN going down more quickly. In actual fact the 125hr & 250hr intervals
are just worst case estimates that the engine builder uses to help ensure
that you're changing oil often enough. If you choose to enact an oil
analysis program you will almost certainly find that you can extend your
service intervals to or beyond the 250hr point even with HS fuel.
FWIW: Engine builders approve of this method of determining service
intervals but for CYA purposes you would be well advised to consult with
them about their requirements for sampling frequency and documentation.
Taxationally yours,
Alex