Ok, so a few weeks ago my girlfriend bought a 1996 toyota camry

, I just got done changing the oil and it looked as if it had been neglected for quite a while oil was almost black and lost most of its viscosity, and it didnt even smell like oil anymore, it smelled like a mixture of gas and ammonia, I know on carbed cars bad seats and flooding will give it a gas smell, but what about fuel inj, and what gives it an ammonia smell?
edit: the car has the 5S-FE 4 cyl
sorry posted in wrong section, can a mod move this to the correct section?