How much differential fluid do I need?
Differential fluid capacity varies by housing size and type. Most passenger car differentials hold 1.5-3 quarts, while truck and performance differentials may require 3-5 quarts or more. See also our Repair vs Replace Calculator.
What type of differential fluid should I use?
The fluid type depends on your differential design and operating conditions. Limited slip differentials require special additives, while open differentials can use standard gear oil.
How often should I change differential fluid?
Service intervals vary by application. Street vehicles typically need changes every 30,000-60,000 miles, while racing or heavy-duty applications may require more frequent service.
Can I use the wrong viscosity grade?
Using incorrect viscosity can cause poor shifting, increased wear, and reduced fuel economy. Always match the viscosity grade to your operating temperature and manufacturer specifications.
What's the difference between conventional and synthetic differential fluid?
Synthetic fluids offer better temperature stability, longer service life, and improved protection under extreme conditions, but cost more than conventional gear oils.
Do I need special fluid for limited slip differentials?
Yes, limited slip differentials require either special LSD fluid or conventional gear oil with friction modifier additives to prevent chatter and ensure proper operation.
How does operating temperature affect fluid selection?
Higher operating temperatures require higher viscosity grades or synthetic fluids for better thermal stability. Cold climates benefit from lower viscosity grades for easier cold-weather operation. You might also find our calculate Volume to Drain, Add Pure Coolant & Add Water — Coolant Mix useful.