I find the #2 vs #1 debate interesting along with the other fuel discussions How about if everyone simply goes to their owners manual or WSM and reads the fuel requirements. Of course this may change with tractor model but below is a copy and past from my
L4740-3 WSM and I've seen similar in other manuals.
Fuel
Cetane number of 45 minimum. Cetane number greater then 50 is preferred, especially for temperatures
below −20 ーC (−4 ーF) or elevations above 1500 m (5000 ft).
If diesel fuel with sulfur content greater than 0.5 % sulfur content in used, reduce the service interval for
engine oil and filter by 50 %.
DO NOT use diesel fuel with sulfur content greater than 1.0 %.
Diesel fuels specified to EN 590 or ASTM D975 are recommended.
No.2-D is a distillate fuel of lower volatility for engine in industrial and heavy mobile service. (SAE J313
JUB87)
Since this engine adopts EPA Tier 4 and Interim Tier 4 standards, the use of low sulfur fuel or ultra low
sulfur fuel is mandatory in EPA regulated area (North America). Therefore, please use No.2-D S500 or S15
diesel fuel as an alternative to No.2-D, or
use No.1-D S500 or S15 diesel fuel as an alternative to No.1-D if
outside air temperature is below −10 ーC (14 ーF).
In another section of WSM:
No. 2-D diesel fuel
No. 1-D diesel fuel if temperature is below ?0 ーC (14 ーF)
So while everyone is worried about diesel fuel, how many are able to buy diesel fuel in their area that meets the minimum 45 cetane rating? My guess is that less than 1% of the folks in North America can even buy the recommended fuel.
Just how important is Cetane rating... It's called out as a root cause in the Troubleshooting Section of "Engine does not start". The 5th item to check is
Fuel with low cetane number. Given that it is 5th item out of 18 listed items to check it is relatively important.