cat converter or transmission sound under car?

97 metro 5 spd ever need transmission oil? I have never put any in 48K mi, where do I check it? New exhaust from converter, could cat. be bad? Do I look for holes in converter?

If you have a leak, it will need oil. 75w90. I would have a mechanic check it. You have to pull the drivers side wheel off to get at the oil check hole. As of your other questions, "new exhaust from converter??" ummmmm, yeah, we'll leave that one alone..... :slap:

I meant new exhaust pipe from converter thru back to muffler. Doesn't leak so don't check it? What's an 02 sensor EGR valve?

If it's not leaking, it's fine. The o2 sensor tells the computer how to adjust the air/fuel ratio for the engine. It's the big plug with a wire coming out of it on the exhaust manifold. The EGR (Exhaust Gas Return) brings exhaust gasses back into the intake manifold. Used to cool down combustion in the engine, and to re-burn some exhaust gasses, for "cleaner" emissions.