[mohanjude]

Everybody has offered sensible advice - do not over rev a motor with no load. We are making an assumption that the OP held the throttle to the max - ie full 6S voltage. If you hold the throttle lightly clearly a ESC will only apply a small proportional voltage. It would be a very foolish thing to do to hold max throttle for full 6 seconds on 6S to see what would happen ot to test how fast the motor runs. On the other hand when I setup my brushless motors for my own safety I always take pinion off the shaft after the motor is mounted to the gearbox to check if the motor spins the right way etc.. I never plug the esc and batteries on a new setup with the pinion on in case the whole damn thing flies off due to a incorrectly setup esc. I blip the throttle to ensure that the motor is turning in the correct direction and to see if the radio needs the servos reversing etc..

Without knowing how much voltage was applied to the motor I really think we cannot be 100% certain that this was the main reason the motor blew. Did the OP hold full throttle or even 80% throttle? Were the Lipos fully charged? Is the ESC faulty? It is possible that for example the windings on motor may have been damaged already and the oil may have had some contribution.