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How to Change the Rear Differential Fluid in an AWD Honda CRV

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Tom Lohr is an avid home DIY enthusiast. He prefers to spend the money he saves on new tools and gardening supplies.

View underneath from the rear of the CRV

View underneath from the rear of the CRV

AWD Isn't Magic, and It Needs Your Love

One of the most overlooked maintenance items on all-wheel-drive vehicles is changing the fluid in the rear differential. If you have a front-wheel-drive CRV, you don't need to perform this maintenance; your vehicle does not have a rear differential.

The rear differential is the meeting place for the driveshaft that comes from the engine and the axles for each rear wheel. There are three sets of gears turning in there, and all gears need lubrication. Unfortunately, it needs to be replaced fairly often; like every 30,000 miles often.

Failure to change out the rear differential fluid risks allowing the gears in the differential to grind together and produce metal shavings that will ruin the differential. It really is an important regular maintenance item you need to pay attention to. If you take it to a mechanic or the dealership for this procedure, be prepared to take out a second mortgage to pay for it. Fortunately, you can change the oil in your CRV's rear differential yourself and save a mint. Despite it sounding daunting, it is one of more easier maintenance items to perform.

Before you start, know that you will be crawling underneath the rear of the vehicle. If you are a really large person, you will need to raise the vehicle to get to the differential. Normal sized people shouldn't have an issue. Regardless, if you raise the vehicle or not, always use chocks or some other means to ensure that the vehicle does not move while you are under it.

Everything you need

Everything you need

Prepare the Vehicle

Park the CRV on level ground. Ensure that the exhaust system is cool to the touch. You will be working around the exhaust, and when your vehicle is running, it gets extremely hot. Use chocks or another method to secure the vehicle to keep it from rolling.

Locate the Rear Differential

You will access the differential from the rear of the vehicle. It is in the middle and is where the driveshaft and the axle for each rear wheel meet.

The rear differential is in the middle

The rear differential is in the middle

Drain plug on passenger size

Drain plug on passenger size

Locate the Drain and Fill Plugs

To change the oil, you will be draining the differential from the drain hole on the bottom and filling it from the fill hole on the top. The drain and fill plugs are on opposite sides of the differential. The drain plug is on the passenger side near the bottom and the fill plug on the driver side near the top. Each can be opened by sticking the square end of a 3/8 inch ratchet in to the square hole in the plugs.

IMPORTANT: Always remove the fill plug first. If you remove the drain plug and drain the differential, and then cannot get the fill plug out, you cannot drive your vehicle.

Fill plug on the driver side

Fill plug on the driver side

Drain the Oil

Once the fill plug is loose, place the catch basin underneath the differential to collect the oil that will drain from it. Drain the fluid. Despite the differential only have less than two quarts of fluid in it, I always use a 15 quart “suitcase” container. Its larger capacity means you can use it for engine oil or transmission fluid changes as well without fear of it overflowing. It makes the job much easier and cleaner.

Drain and Fill plugs removed

Drain and Fill plugs removed

Check and Wipe off the Drain Plug

The drain plug has a round magnet sticking out of the backside of it. This magnet collects any metal shavings that are floating around in the differential. With three large gears grinding against each other, they will shed some metal. The metal caught by the magnet should be so fine that is is more of a paste. If you have actual, identifiable shaving on the magnet, it's time to have it checked out by a mechanic.

Use a paper towel or rag to wipe off the magnet. Then replace the plug after the differential has finished draining. There should be a crush washer (a metal ring) that came off with the plug. If you cannot find it, it is probable in the bottom of your catch basin and fishing around with your fingers should locate it. Ideally, you want to use a new washer, but the old one will suffice if you did not purchase new one.

Note: the crush washers for the drain and fill plugs are different sizes, meaning you will need to purchase two different washers if you plan to replace them. Thanks Honda.

Rear differential fluid with hand pump installed

Rear differential fluid with hand pump installed

Fill the Differential With New Fluid

I highly recommend using the oil made for Honda. Some people will tell you any high quality gear oil will work, but a new differential is too expensive for me to risk it. You only need two quarts, so give yourself peace of mind and by the Honda product.

There is no way you can pour the fluid from the bottle into the differential. You will need a fluid transfer pump. They are cheap and easy to use. After opening the quart of oil, stick the plastic tube protruding from the cap at one end into the quart of oil. That end has a cap that will screw onto the quart bottle just like the original cap, making the chance of spilling it much less likely.

Stick the other end as far as you can get it into the fill hole in the differential. Start pumping. The process is not quick and you will probably need to rest your hands a few times. The differential is full when fluid begins to leak out of the fill hole. It holds just shy of two quarts. When it is full, replace the fill plug.

Pumping in the new fluid

Pumping in the new fluid

Prepare to Test

Use the 3/8 inch ratchet to tighten both the drain and fill plugs. While there are specs for how many foot pounds to tighten them, making them nice and snug will suffice. Do not over tighten.

Wipe down the rear differential with a rag so you can check for leaks after a test drive. Remove the oil catch basin and wheel chocks.

Buy a decent drain pan

Buy a decent drain pan

Test Your Work

Take your CRV for a drive for a few miles and then check for leaks after parking.

Don't Forget the Environment

Used oil of any sort should always be recycled and NOT put in the trash or tossed out anywhere. O'Reilly's, Autozone and other big box auto parts stores will take it and recycle it for free.

The metal mush that wipes off of the drain plug magnet

The metal mush that wipes off of the drain plug magnet

Use This Maintenance Procedure as a Confidence Builder

Vehicle maintenance can be confusing and scary it you have never done it. This is one of the simplest, yet important, vehicle maintenance procedures you can do. Once you complete a job like this, you will be ready and confident that you can do other maintenance as well. Think of the money you can save.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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