2 stroke oil. Super tech from Walmart. Raises cetane makes up the lowered sulphur diesel lubricity. It outperformed many additives in an independent lab that did the results on a diesel truck forum. Someone posted it here awhile ago

I mix it about 1.oz gal. Then I add power service on top. Overkill, probably.
Mpg average 27-29. Gps checked. 180kmi 84SD