Gear Oil Change

Supplies Needed:

Five (5) quarts of 80/90 gear oil, 75/90 is also commonly used
- Designation of API GL-4 is the official spec, but GL-5 is acceptable. Sources vary on the significance of GL-4 vs. GL-5. Straight GL-4 seems to be harder to obtain.
- We used Valvoline High Performance 80W-90. By far the best price is when you buy the gallon jug. It, or an equivalent, should be easily found at your local FLAPS.
- We do not have any personal experience with this, but Swepco 201 is a popular choice according to the interwebs, albeit a little expensive. People can and do debate oils all day, but technically any 80/90 or 75/90 gear oil is acceptable. Find what you like and go with it.

Tools Needed:

17 mm hex socket or allen wrench
17 mm rod coupling nut
- The coupling nut is a make-shift, low-clearance 17 mm hex bit used to loosen the drain plug. Home Depot sells a 7/16 inch rod coupling nut for $1.22 + tax. The OD was nearly a perfect match to the 17 mm hex bit.
17 mm box wrench
Two (2) 13 mm wrenches (to remove the shift linkage)
Funnel with hanging tab
Hose extension for funnel
- Approximately four (4) feet in length. A hose clamp at the funnel connection makes it nice and secure. Home Depot had a 10 foot roll of vinyl tubing for $4.93 + tax. ⅝" OD and ½" ID. Easily trimmed to length. Was a near perfect fit for the fill hole. The clamp was less than a dollar more.
Bungee cord or something to hang the funnel with.
Oil catch pan
Shop towels

Skill Level: Easy / Moderate

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Comments:

Gaining access to the fill and drain plugs will be the most difficult part of the process. The level of difficulty is different for 2WD, 4WD (syncro), and the various engine conversions. In general, 2WD is the easiest to access.

Step 1:

Remove the fill plug first! These plugs are notorious for being difficult to remove. If you drain the oil and then can't open the fill plug you're obviously screwed.

On the passenger side of the transaxle, remove the shift linkage near the fill hole. This is pretty simple, as just two 13 mm bolts hold it in place. (You'll need to use two wrenches.) Once detached, I like to thread the nuts & bolts back in place so I don't lose them.

Just above and to the right of the shift linkage you can see the 17 mm hex plug.

You’ll have easy access by removing the shift linkage.

Step 2:

Now that you have confirmed Step 1, you can remove the drain plug. Make sure you have a sizable catch-pan ready for the oil, it comes out in a hurry!

This van has a Bostig engine conversion. When you try and use a standard socket wrench for removal, it won't fit as the engine cradle causes some interference. So, I had to make my own. I used a 7/16 inch "rod coupling nut" from Home Depot, it cost $1.22 + tax. Bargain. The outside diameter was almost a perfect match. However, I had to use a file and shave off just a hair more to make it fit the 17 mm drain plug.

While the oil is draining, inspect the shavings on the magnet. If yours looks like the below picture, you're probably fine. If you find any big chunks, your days are numbered. Make a note in your maintenance log, or better yet take a picture, then clean the magnet. When you do this again in the future you can compare the difference in shavings.

Standard socket is too big to fit.

17 mm socket on left, rod coupling nut on right.

Rod coupling nut in place, ready to loosen.

Drain plug has a magnet to catch the finite shavings.

Fill plug on left, drain plug with magnet on right.

Here’s how the rod coupling nut works for the drain plug removal.

Step 3:

After the oil is sufficiently drained, replace the drain plug. Considering I didn't have enough clearance for my torque wrench, I just made sure it was snug. (But not too snug!)

Step 4:

Add new oil. I first tried a transfer pump to fill with, as I saw a YouTube video that recommended this. However, this did not work well at all. The combination of the thicker oil and the cold temps made it take FOREVER. After pumping for literally an hour my arms were burning and I made a huge mess in the process. I decided enough was enough and went to the store to purchase the parts for the gravity feed funnel setup. This was still slow, but it was virtually trouble and mess free; it worked so much better! (I don't fault the transfer pump. If I used it for gas, water, or a thinner liquid it would probably work great.)

Depending on your source, it will say to fill until oil comes out the fill hole or until you're within ½ inch of the top of the fill hole. I was shooting for it to overflow, but considering my earlier mess I had wasted a bunch of oil, so I fell short. This was even after buying another quart.

Don’t use this.

Makes a huge mess and the oil is too thick for it to work properly.

Funnel & extension tube. Hang it from the drip rail.

Gravity and patience are your friends.

Step 5:

Replace the fill plug.

Step 6:

Re-install shift linkage.

Step 7:

Clean up, recycle your old oil, and you're done!