Well its not as journal bearings run very similar to crank and rod bearings. Guess garrett in all there wisdom must be completely wrong The journal bearing system in a turbo functions very similarly to the rod or crank bearings in an engine. These bearings require enough oil pressure to keep the components separated by a hydrodynamic film. If the oil pressure is too low, the metal components will come in contact causing premature wear and ultimately failure. If the oil pressure is too high, leakage may occur from the turbocharger seals. With that as background, an oil restrictor is generally not needed for a journal-bearing turbocharger except for those applications with oil-pressure-induced seal leakage. Remember to address all other potential causes of leakage first (e.g., inadequate/improper oil drain out of the turbocharger, excessive crankcase pressure, turbocharger past its useful service life, etc.) and use a restrictor as a last resort Reason td04 may need one is because they are battered and probably nearing the end of their life. Restrictor may just prolong the issue. Ive killed two td04s and think it was down to the restrictor. Line was fine no blockages and both had munched bearings. Primed before hand etc. I can't be fucked to argue anymore, the information is there from experts. Go with whatever...not my car lol