Differential fluid replacements are an often overlooked piece of car maintenance. Fortunately, replacing the fluid is pretty straightforward, so you can likely do it yourself and just have to buy the oil. Don’t know much about differential fluid? You’ve come to the right place.

We’ll go over oil recommendations for your Lexus RX 400h, what differential fluid is, why it is important, and how to replace it. The team behind the super-app and insurance broker

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The best Lexus RX 400h rear differential fluid

Lexus

recommends using the OEM lubricant when replacing your Lexus RX 400h differential fluid. That means using Toyota Genuine Differential Gear Oil LT 75W-85 GL-5. You can

order it from Toyota here

While it may be a bit more expensive to buy the OEM lubricant, it is definitely worth it to help ensure the longevity of your differential. If you are looking for an alternative differential fluid, though, any synthetic differential oil with the same specifications will suffice. The “75W-85” tells you the oil’s viscosity, while the “GL-5” refers to the level of sulfur-based additives. The additives help the lubricant operate under higher pressure.

Here are a couple of alternatives that will work:

Ravenol Gear Oil

Redline Gear Oil

MORE:

Basic car maintenance schedule

What is rear differential fluid—and why does your car need it?

Your car’s differential helps to control the transfer of power from your engine to your wheels. When you turn your car, the inside and outside wheels have to spin at different rates. Your differential controls this rate difference (hence the name), and ensures that your car turns smoothly.

The differential is essentially just a box of gears. You can imagine that without lubrication these gears would quickly get worn down. Differential fluid is the oil that lubricates these gears to keep them running smoothly. That’s why it is so important.

How often to change your Lexus’s differential fluid

It is typically recommended to replace your Lexus’ differential oil every 30,000 to 50,000 miles.

Since gear oil has such a long change interval, and since it does less work than the oil that lubricates the engine, it can be easy to forget about. If you notice any of these signs, then it might serve as a poignant reminder to check your differential fluid:

A burning smell from the rear gearbox

Whirring, howling, or straining noises

Unusual vibrations, especially when turning

It is recommended to err on the conservative side of that change interval, aiming closer to 30,000 miles than 50,000, so that you can change the fluid before any significant wear builds up. To play it safe, you can get your mechanic to check the differential fluid as part of your regular maintenance.

MORE: How to put a car on jack stands

How to change your Lexus RX 400h's differential fluid

If you are looking to save a bit of money and change your Lexus RX 400h differential fluid yourself, the good news is that it is a relatively easy job, as long as you have the right tools. You’ll need:

Car jack and jack stands, or ramps

Socket wrench set

Fluid transfer pump

Drain pan

Nitrile gloves

Before you start, make sure to check your owner’s manual to confirm the exact type and volume of fluid that you need. Once you have collected the oil and all of the tools you need, you just need to follow these steps:

Step 1: Jack up your car or secure it on ramps so that you can access the rear differential.

Step 2: Remove the fill plug first–if the fill plug is hard to open, you’ll want to find this out before you drain your differential.

Step 3: Remove the drain plug and let all of the fluid drain into your drain pan. Fair warning, differential fluid is probably the worst smelling fluid in your car thanks to those sulfurous additives.

Step 4: Reinstall the drain plug and use your fluid transfer pump to fill your differential with gear oil. Fill right to the bottom of the fill hole, if you spill over, it will be messy but not a huge deal.

Step 5: Replace the fill plug, take off your gloves, and give yourself a pat on the back.

If you want to be more thorough, completely remove the differential cover and clean the surfaces. There's no need to go hard with cleaning agents (you don’t want to contaminate your oil), you just want to clear out some of the debris in the old oil. While this isn’t a necessary step, it can help keep things running smoothly and can help prevent leaks.

MORE:

When should I change my transmission fluid?

How to find affordable Lexus insurance

Now that you’ve learned about your Lexus’s differential fluid, why not take a minute to learn about how you can save money on your

car insurance

The absolute best way to find cheaper car insurance is by comparing as many policies as possible. You could do this yourself, or you could employ the power of AI to do it for you!

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