Correct me if I’m wrong but sulfur was always in diesel when refined. Sulfur was’t intentionally added to protect diesel fuel systems.
It was discovered when they began reducing the sulfur content for emissions that they started seeing increased fuel system issues such as injection pump leaks. Without sulfur seals would shrink, harden & leak.
As far as older diesels I wouldn’t be concerned because injection pressures were low (3500 psi) in my 1990 dodge Cummins and even lower in older diesel tractors.
The only time I intentionally dose my fuel is in winter with power service.
I have added marine 2stroke oil on occasion to fuel and it does quiet the engine down noticeably.
It’s you engine and for peace of mind it won’t hurt.
90cummins
Older engines are not immune to damage caused by modern day ULSD because they are old. Neither will running the home heating diesel or off road diesel in the vehicle prevent damage.
"Under Sulphur in Diesel Fuel Regulations (SOR/2002-254), the sulfur content of diesel fuel produced or imported was reduced to 15 ppm after
31 May 2006. This was followed by the reduction of sulfur in diesel fuel sold for use in on-road vehicles after 31 August 2006."
A reduction in Sulfur in Diesel was mandated because, SO2's, are emitted by the burning of fossil fuels or other materials that contain sulfur.
Sulfur dioxide can damage trees and plants, inhibit plant growth, and damage sensitive ecosystems and waterways. It also can contribute to respiratory illness and aggravate existing heart and lung conditions.
Fuel producers when processing raw crude oil left the sulfur in the diesel fuel because it acts as a lubricant. Fuel producer today are required by regulation (SOR/2002-254), to refine the sulfur out of the diesel fuel down to 15PPM and place a Red Dye in Home Heating diesel to show that road taxes were not paid on the fuel. Don't ever get caught with Home Heating oil in a diesel vehicle on a highway.
That's felony tax evasion in the US. The government takes a very dim view of stealing from the Treasury.
In most US states, it's up to 5 years and 25 grand. If you're in the construction or farming trade, you will also lose the right to burn untaxed fuel in your equipment.