Oil viscosity?

[snakebit]

It seems that Tom and most others around here are running xW30 weight. There is some consensus over at Miata.net that xW40 is safer for a FI motor. Has anyone tried 40 weight and gotten it tested? Or has anyone had any issues with 30 weight?

I live in FL - probably not hotter than AZ but very humid and just as much sand flying around!:driving:

[chuckerants]

I know I've always used 5w30 and 10w30 (Mobil 1) as per the Owner's Manual.