The Supplier said warranty is void because i have not serviced the motor i explained i have not used the motor due to ill health 23/4/2017 is the fist time the motor has been use.

Factory parts are advisable but you can buy Subaru branded parts without paying Subaru dealer prices at places like import car parts.

Each vehicle manufacturer has specifics regarding their warranty. To determine if drilling or modifying your frame voids your warranty, it is best to call your local dealer, or contact the vehicle manufacturer. With B&W hitches you can must find out the warranty regulations so as to know what to do.

Have you tried replacing the oil sender switch on engine yet?

On a car that new, still under warranty, I would think long and hard before I replaced the transmission fluid with oil of any type. I would start by calling the service department at a dealer, pay them a hundred bucks to explain your situation before you void your warranty and go a thou or two into the hole.

Never assume anything is assembled as it should be. I generally build engines from the bare block up, but have had several "crate engines" that before install, were discovered to have major items that had not been taken care of. (one that stands out, had rod bolt nuts rolling around in the oil pan, remainder finger tight!).
At the point you are at, I'd do a careful examination of every possibility, beginning with a flush to remove whatever is in there, then doing a system pressure test, cylinder leak-down test and re-sealing the threads on any bolts that are potential seepage areas. If you cannot find anything that reasonably explains the leak, immediately contact your supplier before doing any major tear-down so you do not void any warranty on it.

NOTIFY THE ATTORNEY GENERAL OF YOUR STATE.

The vehicle is under new vehicle warranty.
Take it back to the supplier for waranty repair.

An attempt to fix it yourself may void your warranty claim,

Take it back to the dealer/supplier - it should be fixed under warranty.
If you can't get it back to supplier, take it to the nearest repair/service shop that is authorised to perform manufacturer warranty work.

I can't understand why one would install a used motor in the first place? Also It does however sound like the guy really doesn't want to do the work and won't do it correctly.  I think you'll end up paying a lot for unsatisfactory repair.  You may end up putting more money in the repair than the car is worth.  Good luck   

its at dealer cost if they dont do the work i think it voids the warranty...if you go to a private shop you should be able to get it done much cheaper.but may void the warranty if hey say they have to do the work