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.
My engine is basically stock and recently rebuilt with a stock oil pump. The first few oil changes I used VR1 10w30 because of the zinc and was happy with it. My last oil change I went with the VR1 20w50 as it was the only VR1 I could get at the time and the oil pressure seems kind of high when cold. In my previous motor I was running Mobil 1 and it wore out the bearings I guess it was too thin. Not sure what is causing your sludge but I’d stick with VR1 and possibly try 10w40?
If you are using a flat tappet camshaft, then it is a good idea to use an oil with a high zinc content. The 20w-50w oil is a bit thick for cold starts and it can put a strain on the distributor gear pin during warm up. 10w-40w high zinc oil should be fine for your engine, but that is just my opinion and that is the same weight that I use in my engine.
I use the Valvoline 20W50 vr1 on a stock motor in a warm climate. Never a problema.
On recommendations found in this chat site I purchased 2 cases of VR 1 10W30
The engine is street 500 HP EFI 383 Stroker 2V Edelbrock and Weiand port polish etc.etc.
I live in a warm Hot weather area.
Have I purchased the incorrect weight VR1?
Sorry to deflect from original thread