We put together this capacity chart to help answer the question. Since Motobilt is in the business manufacturing 1000’s of heavy duty diff covers every month we get asked all the time how much should be purchased. This does not estimate how much gear oil you should purchase. Well the general rule of thumb is to fill your diff up until the fluid starts to run out the fill hole.
One question that comes up often is how much differential fluid should be purchased to fill up a diff. Here at Motobilt we get technical questions all the time from simple questions to in-depth discussions.