Welcome to Oscar fish lover
Okay, it's good that you are aware that your tank at the moment is too small for the Oscars you've got. Try and upgrade as soon as possible. I appreciate that your location is probably going to make this difficult. However, for the sake of your Oscars health, a large tank is a must.
If you have twice the filtration for your tank, you are doing okay. Check your water conditions, if you have no ammonia or nitrite present, the filtration is doing the job it is supposed to do. However, speaking from experience, you have two large Oscars in a small tank, your filtration might not be able to keep up with them. You must check for ammonia and nitrite on a regular basis. I'd be very surprised if you don't get trace readings of ammonia and/or nitrite.