Here’s Why Gear Oil Changes Matter
Toyota Tundra Owners: Don’t Ignore Your Differential
If you drive a Toyota Tundra, your truck’s differential works hard every single day. Whether you’re towing a trailer, hauling tools, heading off-road, or just putting on highway miles, the gears in your rear end are under constant load.
And one simple thing keeps them alive:
Fresh gear oil
If you’ve ever wondered:
- “Do I really need to change my diff fluid?”
- “How often should I do it?”
- “Can I do this myself?”
This video and guide are for you.
Your Differential Is One of the Hardest-Working Parts of Your Truck
Most owners change their engine oil religiously—but many forget that the differential is just as important.
Inside that rear diff are:
- Ring and pinion gears
- Bearings
- Clutches (if you have a limited-slip diff)
All of those parts rely on clean, high-quality GL-5 gear oil to survive.
Over time, that oil:
- Picks up metal particles
- Breaks down from heat
- Loses its protective ability
As the video explains, dirty gear oil is like “washing your clothes in dirty water.” It keeps circulating grit and wear material through expensive parts.
Regular changes flush all that out.
How Often Should YOU Change Tundra Differential Fluid?
Here’s a simple breakdown based on real-world use:
Light Duty (Daily Driving)
If your Tundra mostly sees commuting and normal driving:
👉 Every 30,000–60,000 miles
Towing or Heavy Use
If you tow trailers, haul heavy loads, or put the truck to work:
👉 Every 15,000–30,000 miles
Off-Road or Extreme Use
If you wheel your truck hard, hit trails, or do serious off-roading:
👉 After major trips or events
In the video, the owner changes his diff fluid roughly every 8,000 miles because he regularly tows over three tons. That’s more frequent than most people need—but it shows how serious use justifies shorter intervals.
This Is a Perfect DIY Maintenance Job
One of the best parts about differential service?
It’s very DIY-friendly.
With a few basic tools, you can do this in your driveway:
- Socket set
- Drain pan
- Fluid pump or syringe
- New gear oil
- New crush washers
The video walks through the entire process step by step, including small details that make the job easier.
Important DIY Tips From the Video
If you’re planning to change your own diff fluid, these points are crucial:
1. Always Open the Fill Plug FIRST
This is one of the smartest tips mentioned:
- Crack the fill plug before you drain anything.
Why?
Because if you drain the differential and then discover the fill plug is stuck—you’ve got a big problem. Opening the fill plug first ensures you don’t end up with an empty differential you can’t refill.
2. Use the Correct Gear Oil: GL-5 Only
Not all gear oils are the same.
Your Tundra differential requires:
👉 GL-5 gear oil, typically 75W-90
It’s important to know:
- GL-4 oils are for transmissions and transfer cases
- GL-5 oils are for differentials
Never mix them up.
Using the wrong oil can cause poor protection or even damage over time.
ENEOS Gear Oil 75W-90 is produced by an original equipment manufacturer (OEM) supplier. Trusted by OEMs, ENEOS has all the specifications and produces fluids like gear oil for Japanese OEMs.
3. Don’t Just “Fill Until It Overflows”
Toyota actually specifies that the fluid level should be:
👉 0–5 mm BELOW the fill hole
So if oil is pouring out, it may actually be slightly overfilled.
The correct method is:
- Fill until it just starts to weep
- Let it settle
- Plug it once it stops dripping
4. Replace Crush Washers
Every time you do this job, spend the extra couple bucks on new washers for:
- Drain plug
- Fill plug
It prevents leaks and headaches later.
5. Do the Job on Level Ground
This sounds obvious—but it matters.
If the truck isn’t level, your fluid level won’t be accurate.
Choosing the Right Gear Oil
In the video, they use ENEOS 75W-90 LSD Gear Oil, which is designed to:
- Meet OEM factory specs
- Handle heavy loads
- Protect gears under towing conditions
- Work in both limited-slip and standard diffs
The key takeaway for DIY owners:
Don’t cheap out on gear oil.
Good oil = longer-lasting gears.
A Simple Maintenance Step That Saves Big Money
A new Tundra differential is expensive.
A few quarts of quality gear oil and an hour of your time?
Not so much.
If you tow, haul, or plan to keep your Tundra for the long haul, regular differential fluid changes are one of the smartest things you can do.
Bottom Line
For Tundra owners, differential service is:
- Easy to do yourself
- Relatively inexpensive
- Extremely important for longevity
If you’ve never changed your gear oil—or don’t know when it was last done—consider this your reminder.
Watch the video above, grab the right oil, and give your Tundra the maintenance it deserves.
Your truck will thank you with many more miles of reliable service.