smoke

[aniqq1]

I have MEHRAN VX 2007.(26000 K/M) when i switch petrol to CNG, black smoke is exahausted.after 3,4 minutes it normal.
car reducing oil level
it happens only if car runs a few k/m on petrol and switch to CNG
what could be the problem

[wonder_guy]

Black smoke isn't sign of weak engine...its the blue one....

[immad100]

if you are getting black smoke that indicates=un-burnt fuel coming out as it is.
white or blue smoke are the sign of weak motor.
get it properly checked.