Theory of Operation The turbocharger oil supply line supplies oil to the turbocharger from the filtered side of oil filter adapter. Oil returns from the turbocharger through the drain line. JC89288,000003E –19–30JAN06–2/2 9010 05 10 TM2361 (24JUN08) 9010-05-10 450DLC Excavator Operation and Tests 062608 PN=258