If your worry is premature wear of the original injection pump barrels in your 123 pump, your worry is warranted.

You don't, however, need to use an expensive additive. Simply buy some cheap 30W, or whatever, oil. I got some private brand 30W that was as golden as honey. Pour in just an ounce or two per tankful. That's all it takes.

When the sulpher content was lowered in the early nineties, I was warned about the sudden high failure rate of injection pumps so I began adding a splash of oil every fill up. The car went several hundred thousand miles after that with NO injection related problems.

Your other alternative is to rebuild the pump with the hardened barrels now available from Bosch or MB. They are about $100 each plus labor in the clean room, plus labor to R&R the pump.

Good luck,