The differential uses heavy gear oil to lubricate the gears that send power to your wheels. It runs hot under load, so periodic changes keep the gears protected, especially if you tow or drive hard.
30k-60k mi
typical interval
$80-$150
cost per differential
📊 Quick Comparison
Item
Typical Interval
Cost
Differential fluid
30k-60k mi
$80-$150 per diff
Severe/towing use
shorter interval
$80-$150 per diff
Typical interval
Differential fluid is commonly changed every 30,000 to 60,000 miles, though some vehicles specify longer intervals. Check your owner's manual, and note that all-wheel-drive and four-wheel-drive vehicles may have front and rear differentials plus a transfer case, each with its own fluid.
Use the exact gear oil grade specified (for example 75W-90)
Some limited-slip differentials require a friction modifier additive
Severe-service driving
Towing, hauling, off-roading, and frequent hard use raise fluid temperature and can call for shorter intervals. If you tow regularly, follow the severe-service schedule in your manual.
Limited-slip differentials
Limited-slip differentials often need a specific friction modifier added to the gear oil. Skipping it can cause chattering during turns, so verify the requirement for your axle.
Signs of trouble
Whining, humming, or rumbling noises that change with speed, or a burnt smell from the fluid, can indicate the fluid is degraded or the gears are worn. Have it inspected promptly.
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❓ FAQ
How often should differential fluid be changed?
Commonly every 30,000 to 60,000 miles, though some vehicles go longer. Check your owner's manual, and remember AWD and 4WD may have more than one differential.
Do I need special fluid for a limited-slip differential?
Often yes. Many limited-slip units require a friction modifier additive to prevent chatter in turns. Confirm the requirement for your axle.
What are the signs of bad differential fluid?
Whining or humming noises that vary with speed, rumbling, or a burnt smell from the fluid all warrant an inspection.
Does towing change the interval?
Yes. Towing and off-roading raise fluid temperature, so follow the shorter severe-service interval in your manual if you do either.
Can I change differential fluid myself?
It is doable with the right tools and fluid, but some differentials have fill and drain plug quirks or no drain plug at all. Verify the procedure first.