whats the best synt oil to use,

 

I have Mobil 1 in my 3, Valvoline SynPower in the wife's ride, boat has Amsoil, and one of my bikes has Royal Purple in it. Makes no difference to me so long as it is full synthetic.

There are a couple previous threads on synthetic oil, give them a search, a couple were pretty good. Check this one RE: when to switch to synthetic?

 

I personally only use 0W-30 Mobil-1 Synthetic. It was recomended to me for my 500 hp supercharged 350z and Ive never had problems with it

 

I use Amsoil 5W-30 although a lot of people who use Amsoil swear by the 0W-30 signature series. I find it really increases your MPG. Went from NY-ME yesterday and got 23mpg. The only other thing I did was replace thepaper element air filter with a K&N substitute. Everything else is stock.
Amsoil also makes an engine flush when you initially switch from conventional oil to fully synthetic.

 

I use ROYAL PURPLE in my 07 H3,,,,I also use ROYAL PURPLE in EVERYTHING I own now,,,watch to many 4x4 shows on TV showing Royal Purple usage and even in my BRAND NEW 07 BULLDOG BIGDOG....Everything runs COOLER and less Wear and tear

 

I use Esso 0W-30 full syn. in all my vehicles year round, I've been doing this for years and have had no problems, the main reason I went to the 0W-30 was for peace of mind when it's -40 outside.