Hi, new here, hubby was an auto tech but recently passed away. My 2012 Nissan SL with 128k miles apparently has a leak in the turbo. High pitched whining and some oil leaking. My questions..can just this piece be replaced? Is it worth replacing any of it? Can I use the cheaper knock off parts or used from a pick and pull/scrap yard? I see videos of how to replace the entire system, and I am not afraid to get my hands dirty and use his tools, but I'm not sure which direction to take. TIA.