I've posted this before, but this seems like the thread to say it:
In my FC, I have used synthetic before and it smoked like crazy. Specifically here is what happened: Picked up my seven from gotham racing, drove it out the lot, down the block and all the sudden it's like james bond turned on the smoke screen. so I turned back in and was like WTF guys? So, a month later I call em and they say "Oh yea, we put synthetic in there when you picked it up and it just doesn't like synthetic, we put non-synthetic in and it runs fine." So either Gotham was BS-ing me or our cars are pretty individualistically tempermental when it comes to oil.

Water Wetter
 

I put water wetter in my FC and with in a week it was smoking like a mo fo. I'm not sure if it was the water wetter or just its time to go.

If you're talking about synthetic crankcase oil, I put synthetic (Royal Purple) before my drive from California to New York. No real problems related to oil along the way. Maybe it's the brand of synthetic or maybe they're just bullshitting you.

my .02

ELF is a great brand of synthetic oil. it is a TRUE 100% synthetic oil unlike these US market oils (quaker, mobil, penz, valvoline etc)

Mazda has writen an article about how they recomend ELF oil to be used in the RX8 when using synthetic oil...

Well if they have now figured it is good for the RX8 it will be fine in the 7..

I use the ELF 10w50 in my 7 and it loves it.. hell I sold it to another guy on here to .. I am sure he will like it..

I use the ELF oil and the ELF semi organic antifreeze in my car.

I wont use anything else in any other car

btw here is a link to their site

http://www.elfmoto.us/lub/lubusa.nsf...?OpenDocument&