register yourself at withyouhamesha.com http://http://www.withyouhamesha.com/
for service details for every Mahindra vehicle.
Engine treatment is not necessary at all. it doesnt make that much of a difference as Hyderabad is generally dry. You can get it done once a year or so.
Chk out the differential oil detials in your user manual if it says it needs to be changed in the 2nd service it will have to be changed as otherwise Mahindra can claim negligence on your part and void you off the warranty. better still make a call to customer care number of mahindra xylo and get your doubts cleared.