Discussions about oil are a touchy thing. People get tired of the same rants from the different camps. I'm going to give you the short version of my theory and then if the others want they will do the same but I will not argue this subject. I just think you need this info at the beginning so you can move along.
I'm not aware of any additives that work.
What is need is a compound known as ZDDP. Other oils have this. They are usually advertised as Older car or Motorcycle oils. But not all these products advertised as such do contain ZDDP. There is apparently some way to Google this info and I have tried but I don't get the info I want. We have a dry clutch so Motorcycle oil is not always right either.
What I do know that works is BMW Motorcycle Oil that I buy at my local BMW Motorcycle Dealer. I use only the 20/50 wt which is what my motorcycle was built to run. I save a little bit of money by buying in the one gallon size but it's not much savings. This oil is expensive. The only alternative to the BMW Brand oil I use is Sectro 4, also in 20/50 wt. This is almost the same oil as the BMW brand I am told.
Somebody will suggest an over the counter major brand. As long as it has enough ZDDP it should be OK.