I have used lucas HM and lucas pure synthetic in the past and it has worked pretty well to be honest. I have seen the voa for the normal oil stabilizer and I understand it's pretty much just thick oil. The high mileage isn't probably a whole lot different other than seal conditioners. I don't know about the pure synthetic. However I was thinking about using the modern engine one. Has anyone tried this? If it's a flop i have used the lubeguard biotech before and was impressed as well and may switch back.