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...
I am sure Larry has taught a lot of classes, and he knows a lot about engines. I am kind of wondering what he knows about oils though. I was gone for a few days, but others already beat me to it, the type of oil he is listing is not available. You can find oil that exceeds the standard, but oil has changed a lot over the years and like I said before, I recommend Lucas
Larry is more than welcome to recommend oil that is obsolete, impossible to find, and not produced today. I just buy Rotella for diesels and add Lucas to help keep the oil where I want it, you can do what you want to do with your engines.
I know there are people with a LOT more experience than I have, just like I have a LOT more than most people do, but I give my opinion based on my experience. I get a lot people who seem to think that my being in Texas or my being a full time oilfield mechanic working on both old and new engines somehow translates to my not knowing my stuff well enough to work on a 1975 model engine. Fine, I have too much work as it is, and have had since I was a kid, take your engine to someone else, get your free advice from someone else or not, it makes me know difference at all.
I have my own engines to work on too, and I am trying to get time to do them, but it seems that other people's engines keep getting in my shop and I do not have the time or the room to do any more than I am right now.
My brother told me once not too long ago that the reason he never gives out free advice and consultation is that the people asking are just going to argue, and not do what you advised them to do anyway, so why waste the time? He is certified with Cummins, Mack, Caterpillar, Detroit, Perkins, and a couple of others as well as Allison, Eaton, and some of the others, and together we have done a few mechanic jobs over the years, but no one wants to listen to the things people getting paid to do the work have to say. Instead they go around until they can find someone who agrees with them.