So theres the rub. Brand new clean moisture free plant oils will keep the system lubed better.
Dirty gritty moisture laden grease will wear them out and plug them up with polymerized "chicken skin" and also coke them pretty bad if not being injected at high temps. So a good system is one challenge, knowing only to use it at full temp ( monitoring injection temps and if its not injecting hot enough modifying things) is another and the most critical is actually getting large amounts of oil and filtering/dewatering thoroughly enough.
At $2/ gallon its wasted time. At $4/gallon its a great idea but only if you dont wreck your truck doing it which is easier said than done.
You can certainly pour a quart of cheap motor oil into your diesel tank and get the lubrication up.
God Bless America