Hi guys , some advice needed please . I have a 350z roadster , 37000 0n clock , full service history and was seviced 500 miles ago . Have owned for just under ayear and only done 1500 miles in that time . I have just noticed in mornings when first starting from cold its smoking grey then white smoke from exhausts for about 10 to 20 seconds then nothing ? Apart from first thing in morn , nothing at all , even if left to cool down for 4hrs . Have checked oil / water for contamination , no problems found , head gasket starting to go ??? Is there a pressure check the garage can do ? Sensor for fuel mixture ? Any ideas chaps , Thanx barney .