Well i used to be conventional all the way. and used the good stuff in my motors etc . The new engine on my boat after using the break in oil for 20 plus hours was supposed to switch to a synthetic oil as per warrenty.
SO i called volvo guy, He was awesome of course he said the use the volvo stuff and then asked about "Royal purple" he said it better than what we use and NO it wont void warranty as its exceeds etc etc etc.
I then asked old way id swith out after 50 hours or so.. he said with these new oils (synthetic) we recommend 150 hours changes. got to admit kinda was ok??? but after reading the qualities of it can see why so im actually SAVING money, especially a few weeks ago they had it on sale and a major parts store clearing them out at $8.99 a litre so i bought 3 cases, im even going to start using it on the yammy kicker....