I have 2015 CX-5 KE Series Maxx Sport AWD 2.5i Petrol 154000 klms and Coolant Started Disappearing , We bought the car 2nd Hand from a Dealership in Newcastle NSW , Was going great until this happened , Took it to a Mazda Dealer ( 150 klms away on a car trailer),
only to be told the motor is contaminated with water in the oil and we should replace the motor at a cost of $22,000 , Mazda mechanic thinks its a faulty Head Gasket , Car didnt get hot cause everytime it got low on coolant ( Total 3 Times ) the computer shut down the Motor
before causing anything major to happen , Wondering if anyone Else has had similar Problems and what to Do , The Mazda Dealer Do Not want to fix it , unless I am willing to put a New Motor in it , which I cannot afford.

 

You said it shut down 3x which worries me as you should've immediately addressed the issue after the first shutdown.
You might have possibly been able to fix the issue at that time without a motor replacement.
It's unlikely replacing a head gasket at this point will work but it is your cheapest option but no guarantee the motor isn't already toast.
You'll need to find the actual cause or causes of the contamination and decide what to do from there.
The cost they are giving you for a motor replacement seems very high to me.
Average Mazda motor replacement is around $5000 US or $7500 AUD

 

Welcome to the forum

Sorry to read about your troubles.