• Front Axle - SAE 80W-90 Axle Lubricant GM part no 1052271 or SAE 75-90 Synthetic axle lubricant GM part no 12378261 (Grape Juice)
• It is recommended to replace vent cap with GM part no 12479296 when using a synthetic lube
My question is what is a vent cap and why would you have to replace...