looking for suggestions i have a 73pantera previous owner rebulit the engine to boss 351 specs 11.7 comp.closed chamber heads close to 600 lift comp cam.so its a beast.the engine was built in the late 90s and has less then 10,000 miles on engine 32,400 on the car.anyway i was using 20w 50 vr1 valvoline only because i figured this particular engine needed the high zinc in the oil.i was changing the oil about every 800 to 1000 miles with a 10 court pan.my issue i let go maybe 1500 miles and the oil is dirty as hell with small amount of sluge.do i really need to run this type of oil for street use plus it does sit alot.puzzled by the sludge.
Original Post