@ehsaniuk
1.Change engine oil at regular specified intervals.
2.Keep car in well tuned condition.
3.Always keep your CNG settings correct.
4.90% of the time try to change gear below 3500rpm
5.Always try to run your car when the engine is properly warmed up.(If you need the car immediately always remember to acclerate the car lightly and change gear at low rpm and avoid putting load on engine).
6.Like storm said let the car stretch its legs once in a while when it is at normal operating temprature.
7.Use A.C as less as possible, especially in inner city driving.
8.Under no circumstances and i mean no circumstances ever let the engine overheat.
9.Always keep check on other things like suspension alignment, tyre pressure, etc as they put unnecessary load on engine.
10.Last but not least, avoid giving your car to other people to drive, a car driven by only one person and according to his habits usually lasts longer.(my personal experience)
(Thats all i can think of right now, maybe more later)
