White smoke from exhust

I recently had an oil change, some weeks after (maybe two) my needs servicing light came on. "Knowing that it's that time, I have not hurried to have it service.
Some day's have passed and now I have white smoke coming out of my exhaust.

Idling putt-putt, like it wants to stop, pressing on gas at a red light and it's hesitant.

What's Wrong?
What should I have done and what should I have them NOT do when I take it to the shop!

:(