It appears that most of the information given above is the opinion of the respective posters. I see no exclusion for diesels listed in the Members Benefits.
GOOD SAM PLATINUM+ ROADSIDE ASSISTANCEEmergency Fuel
and Fluid Service
If the Member’s vehicle runs out of fuel, a limited
supply of fuel will be delivered to enable
the Member, Associate or Extended Family
Member to reach the nearest fueling station
(up to 5 gallons). Other essential fluids needed to enable continued
safe operation will also be made available, including antifreeze,
transmission fluid, differential and transfer case lubricant.