If it has been in both system then there shouldn't be much wear but if it's been only gas usage then you will find yourself doing engine overhaul later down the road.as problems associated with only gas usage engines are carbon build up, valve seat and guide wear,ring wear as these things don't get lubricated sufficiently.
As desert warriors have to be in peak condition anything less will not last...
If you can get history of the vehicle and or get a compression test done and see if the numbers you get compared with minimal and maximum from the manual of manufacturer...that way you can gauge where the engine is standing...
Other than engine nothing gets affected the rest of the drivetrain will age as usual...