Air filter, might even be a FIPK and pulley from what I can see real quick.
I was gonna say as well looks like K&N and a pulley I'd get it tuned for peace of mind. Oil as in motor oil? If not could be the differential.
You could also check the oil cooler and see if it's just blowing back when driving.
The pulley measures 3.25". Stock is 3.65?