Why the LS Has a “Bad” Oiling System Ever wonder why the LS oils the valvetrain first instead of the mains and rods like a real race engine? The LS uses a priority valvetrain oiling system — oil travels from the pump to the filter, up through the lifter galleys, then down to the cam bearings and mains. So your rods and mains are last in line. Sounds backward for performance? It is. But GM designed it for quiet, low-RPM street engines, not race cars. Why GM did it: • Reduce noisy lifter tick & wa