Based on what I have seen at the Various Pro Races at the Tracks around my House,,,,,The Pros and accomplished Amatuers run Lighter fluid in the Front Diff, most of the Time.
You can Tell by looking at the Tire wear patterns on their Buggies and Truggies. The front Tires are always nearly Bald at the end of the race. This indicates to me that they are Spinning the Fronts a lot more to aid in Steering.

They run this way, even though the tracks around here are Hard Packed......