Volkswagen recommends checking your differential fluid every 30k miles as bad fluid can lead to premature wear.
This kit includes the fill plug, seal, and 1 liter of Motul 75w-90 fluid,
MOTUL Gear 300 is a 100% synthetic lubricant for gearboxes and axles specially developed for competition cars: racing circuit, rallies, and endurance trials. In all types of cars, under all conditions of use, this oil has proved it's quality and resistance to extreme pressures