Funny...from what I've read in just as many wasted hours I've come to understand that synthetic oils are OK. But IMHO if you do regular oil changes and are not racing it's not worth the extra money.

I think the definitive answer on what weight to use is that page from the Australian owner's manual that has a "which oil" vs temperature chart. Almost every weight that's been recommended here is acceptable.

Ken

 

https://www.rx8club.com/showpost.php...4&postcount=28

And i personally saw a couple of engines have problems with the mobil 1 we get here on the long term. It doesn't even mix as well as other oils though, not much worse but not the same as others like valvoline's and royal purple's products.
Of course we don't have much money to try stuff but add our small, minimal tests to a way bigger knowledge and you know that you can avoid buying some brands if you have other chances.