Mobil 1 5W30 Being Burned Like Crazy?

[416BRAND]

2005 Maxima SE. 173000 KMS (107497 Miles) I am going through 1 small bottle which is what about a Quart or basically a Litre if you will every month. My average speeds are around 120-140kph (80-95mph) on the highway give or take. I have no oil leaks that are visible mechanics have checked and no spotting under the car. I use a great oil filter, Purolator PureOne. I have new NGK platinum plugs. New throttle body. New PCV Valve. Been burning it all summer spring and now fall too apparently. ITS ****ING EXPENSIVE. $15 for one small bottle. $60 for the large 4.4L bottle. Which is what the car takes for a change just about (4.25L to be exact I believe)

Is this what you guys are burning on yours?

I've owned 3 4th gen maximas running Castrol GTX and I never had problems. I never had to top up my oil once between changes. Now I'm topping it up every 2 weeks on my new max.

I ran Redline complete fuel system cleaner back in the spring. It smoothed the car out a bit. But eh... I can't think of much else to do.

Should I just switch back to Castrol GTX? Its literally 1/3 the cost of Mobil 1. What performance am I really getting here if I have to constantly deal with this.

[416BRAND]

Some guys in another forum mentioned that it could be clogging precats. Which reminded me... mechanic told me that there are some drill holes in the cats, appearing that someone had checked to see if they were clogged previously. Guessing they weren't since nothing was replaced.

I have an exhaust leak where the downstream passenger side o2 connects to the pipe, thats just below the precat. I have a o2 sensor code because of it. There is also a small leak at the front of the system where it comes down from up top. The rest of the system seems good. Could this loss in pressure throw off the computer and other items potentially causing this? I've been to 2 dealerships before and 3 local shops, they all said no that isn't the cause they said these cars just like to burn oil.

I plan on replacing the entire exhaust system maybe excluding the mufflers since they don't need to be replaced - in the spring. I've been driving with the minor leak for months. At 1500 RPM the car vibrates a hell of a lot because of it but everyone said its ok to drive like that since I don't have the money right now to replace the exhaust system with all 3 cats. Hm.