We have a 2014 with 90,000 miles. Took it to the dealership for blowing white thick smoke out of the tailpipe. Dealer is telling us that the entire engine needs to be replaced because of sludge build-up. They are trying to say it is from lack of maintenance. We have owned the car 18 months and maintained it properly. The car was JUST at the dealership 2 months ago when they replaced the transmission. We didn't even have any problems, just told us we were getting a new transmission. Thankfully, it was covered by Infiniti. The dealer changed the oil at that time. How was there not a problem detected then?? I am so confused as to how a 3 year old high end car can need a new transmission and a new engine?? Do I have any other options other than replacing the entire engine?? Has anyone had luck with removing sludge? I love this car and have bragged about it to others so much that 2 friends went out and bought Infiniti's!!

We have an extended warranty, but the claim was denied. Are there any other options other than replacing the entire engine?

Sludge wouldn't cause that. It sounds more like a blown head gasket.
Can you ask how they determined it was sludge buildup, and also why they replaced your transmission?
If nothing else, I'd at the very least take it somewhere else for a 2nd opinion. Did they say why the warranty claim was denied?
Being that you've only owned it 18 months, you really shouldn't have a problem here...