Fuel and oil additives

I am about to service my Dresser TD7G with the Cummings Engine before I use it this month to do some log hauling and dirt moving on my farm. My question is what is the opinion of fuel or oil additives to keep this machine humming away. The interest at this time is purely preventive as I don't have any major issues presently. Are using additives like Gumout 51001 Multi-System tune up a good idea, bad idea or just a waste of money. I do have a small loss of hydraulic fluid and gear oil...

Fuel and oil additives

Fuel and oil additives