The Ripper, by changing the composition, to low sulphur,some seals and O rings can swell or shrink,
Most engines made after 1994, have fuel system seals and O rings made of Viton( also known as FKM ) which is not affected by the low sulphur fuel.
Older fuel systems( more than 8 years old ) may have seals made from nitrile rubber (also known as NBR or buna-n )which is not as resistant to the changes in the fuel composition as Viton.
The older seals can easily be changed to Viton, during a maintenance service.
Over here a diesel lubricity specification has been introduced as part of a mandatory national fuel standard, which all diesel fuels must meet.
But if you have concerns about lubrication, 1 litre of vegetable oil to a tank of fuel should be more than enough to guarantee the injector pump is adequately lubricated. Personally I would be doing this if I were you, the oil should increase the life of your injection pump.
I don't know the optimum proportion of oil to low sulphur diesel, but if you consider I litre of oil to a tank, as a minimum, you could add several times that without any problem.
Low sulphur diesel is less corrosive than the high sulphur fuel, so using the lsd at anytime should reduce engine wear.
I hope this has been a help.
Kind regards...Ron.