So I had this exact same thing happen. Only I was burning white smoke and going through literaly, 1 qt every 100. Yes 100. Miles. I had been putting it off, putting it off, thinking it was just my injectors, but then I started hearing a knock and a sputter and then came my tax refund so here I am doing a complete rebuild. I found my #8 cylinder had a broken ring, but all my bearings looked great. Got the engine dropped off at the machine shop for some over bore love and then dug into my turbo.
1st off, my banks sidewinder didn't have an ID plate on it... So after many many hours researching these, and talking to banks I got a manufacturer part number for the entire turbo, the cartridge, and the housing. Fyi, don't screw up your cartridge, banks wants like 1300 for just a new cartridge. But anyway. You need to know exactly what turbo you have. Probably a TE06H, like 25A is what mine was. Find mamba on ebay, contact them to get rebuild kits for your turbo. All new seals and bearings and hotside and coldside piston rings. Like 80 bucks max. Know you have asuperback wheel or flat back. When reassembling, lube up back plate and o ring and put it on by hand and don't force it.
Anyway, my turbo was leaking like a sombich right behind compressor. Probably my worst oil leak problem. Was also told by banks by CDR might be bad, but I think I just replaced it too. Oh well, off for a new one of them too. But now I have new stanadyne G injectors, new bores and pistons, lower compression, and one of Typ4's splendid cams paired with a fresh turbo. Not together yet, but should run like a bute