Oil from exhaust, dead coilpack, o2sensor bad

[Fungist]

Hi bought a cheap t25 that ran on 3 cylinders

2003 1.8vvti manual. 

 

I decided to just buy the car as i got it so cheap. 

 

I scanned the car and got code for dead coilpack on cyl4. 

I dont know for how long previous driver have driven like this. 

 

Car was low on oil. I actually managed to top up 2 liters oil. 

 

After replacing the coilpack, car finally runs good. 

I cant feel any powerloss or anything, as i had my fingers crossed the cat wouldnt be too bad after running on 3 cyl. 

 

Im getting a code for bad o2sensor (post cat) 

Car also throws code for cat, but car runs fine so im hoping it will be solved after replacing o2sens as the post sensor may trigger a cat code if gone bad. 

 

Now i just wounder, some oil getting out of exhaust. 

May this be buildup in cat, due to car been running on 3 (i dont know how long) or any other reason i might be looking at? 

 

Car obviously uses oil as i had to top up from previous owner not giving a F. 

 

However i just wanted a cheap car to use to work and back home, it's not lacking power, but a bit surge at idle, i guess due to o2sens. 

 

Thanks.