As someone with over 25 years of experience in maintaining and repairing diesel engines I recommended the use of Power Service and Lucas Oil Additives, this is because I know a whole lot more about diesel engines than most of you will ever know. These are not "secret sauces" they are tested and proven commercial additives used by companies like J.B. Hunt, Schneider, Swift, Werner, Halliburton, KBR, Nabors, and hundreds of other large companies because it works. Now if you want to listen to someone who is not a diesel mechanic, has zero diesel engines in his shop to be rebuilt, and thinks that most marine diesels do not have glow plugs because he has seen one or two without them, go ahead.
I hate giving advice on here because there will always be some ding a ling who thinks he knows more than someone with literally thousand of hours of training and experience who will come along and tell everyone how the expert and highly trained professional is wrong. I wander if a doctor were telling you that you should take a certain medicine if you wanted to live longer, would you go to a palm reader and take their advice instead? Would you prefer the advice of someone who earns a six figure income because he knows diesel systems, or the advice of a person who sells doughnuts or something for a living?
Here's a response back from Mack Boring in particular Larry Berlin, Service Trainer, when I specifically asked about Lucas additives in Yanmar engines.
I remember he saying from taking one of his classes that additives are not recommended but to make sure there had been no change in their policy I went ahead and asked for clarification on the product mentioned
Hello Mr. Owen,
Yanmar does not recommend any oil additives.
They recommend you use a high grade 30W or 15W40 viscosity oil that meets
or exceeds API specs of CF4 or higher. Mack Boring follows these recommendations.
Oils meeting these specifications are readily available. Follow the oil change intervals
as given in the operators manual or once a season whichever comes first.
Have a great boating season.
Larry L. Berlin
A Division of Mack Boring & Parts Co.
Phone 908-964-0700 ext 298
..Just an FYI..Larry Berlin has probably taught more mechanics as well military personnel in the subject of diesels than most..so I have a great respect for his wisdom...