would there be any harm in using a Dino 75w90 gl5 to top off a few tenths of a quart in a differential that has a Synthetic 75w90 GL5 of the same brand Valvoline. im asking cause my truck has a transfer case 1.1 quarts,rear differential 3.2 quarts and front differential 1.60 quarts instead of buying a full synthetic at twice the cost just for topping off the couple of tenths needed to fill.