No need for overhaul not unless may problem talaga makina mo. You can read the lc200's manual na its normal yun ganyan not just for the 200 but also for fortuner. You need to top up talaga on the 200.

I cant recall which australian forum i read they also have the same issue you can change the oil something ek el but it will not guaranty the problem, just do a top up regulary.

Btw tinry ko hindi mag top up, it averages 1-2ltrs ang kulang after 5t kms