Bmw Engine And Engine Cooling Engine Gasoline Turbo-charger

1997 BMW 740 IL check coolant indicator came on and then checked and filled coolant. but then 4 days later filled up gas tank on business trip(used regular grade of gas at unknown gas station that was closest) in evening then come morning when I

my 2008 335xi bmw has 43 thousand miles. I was driveing it tonight and the engine light came on and it started running rough.When I acelerated it act as if it wanted to stall.

when cold, 1986 bmw 735i  hard to start...gas leaking onto left side(drivers) manifold or engine block.  sometimes intermittant.  

Have 2003 Z-4 M54 engine with 83,000 miles.  Driving along and smoke started to come out of the exhaust then alot of smoke and car quit running.  Repair shop says it blew a head gasket which damaged the engine.  No warning lights or services e