It means the Rotella has the desired zink content, does not soot(the  
diesel itself does that) and stands up to the extreme bearing load a big  
diesel goes through.
Yes, there are non diesel spec oils on the market which works well, Royal  
purple has been mentioned, as have other small U.s. only companies.

Rotella has been around for a long time being made(blended) by a well  
known company.
It is your money and your choice..

If you care to read through some of Rabys writings and less than  
scientific testing(he swears to hands on..), he has come up with a small  
U.s. blender which supposedly is great, his words not mine..

J.

I think the point is this:
If you have lots of money &/or just like to know that you have the
latest and greatest motor oil in your sump (& there's nothing wrong
with either) then there's really no argument to be made.  My point was
based on value/price vs. the effective life of the motor oil.  With
typical carb setups, any oil you put in there will have to be changed
in a relatively short time due to fuel contamination.  While some of
the botique oils might not shear down as quickly, they'll still have
to be changed at a short OCI.  Among the more reasonably priced oils,
the HDEO's for big-rigs are (IMO) the best, because they have to meet
the heavy demands of commercially operated diesel engines and don't
have to concern themself as much with negative effects on gasoline
auto cat converters.  Certainly,  some of the "true" synthetics like
Mobil1 15-50, RP, Amsoil, Redline, etc. are great oils, but maybe not
great enough to stretch out an OCI in a carbed motor when the same
money can buy multiple 5-gallon jugs of good HDEO allowing numerous
oil changes for the same (or less) money.
JMO.
Bill.