How do you add gear oil to a 1974 VW thing transmission?

If you haven't changed the oil recently--say, within the last year or so--I would just go ahead and change it.

You will need:

three quarts of either 75W90 or 80W90 hypoid gear oil. Synthetic is really nice if you can afford it; it makes the transmission shift just so nice. The car will work with either weight of oil, and normally an auto parts store will have one or the other but not both.

four feet of the largest-diameter fuel hose you can get

floor jack and four jackstands

tools to remove a tire with

17mm Allen wrench. Sometimes you can get these set up as sockets, and those are really nice.

drain pan

LOTS AND LOTS of rags

Process:

1. Loosen the lug nuts on the left rear tire, jack up the car, get under it and remove the top drain plug. Never, ever remove the bottom plug (which holds the oil in) if you can't get the top plug (where you put the new oil in through) out of the transmission. Once it's out, clean it well and put it somewhere safe.

2. Put the drain pan under the transmission and remove the drain plug. Clean the oil from your hands.

3. Inspect the drain plug closely. It is magnetic. There will be metal shavings stuck to it. You are driving a 37-year-old car so this is okay. There should NOT be chunks of metal stuck to it. If there are, go on the internet and find a rebuilt transmission because yours has had it. This doesn't happen often but it can so watch for it. Clean the crud off the plug.

4. After all the oil drains out, reinstall the plug. Get it good and tight but don't get stupid because your transmission case is made of aluminum.

5. Pull the drain pan over so it's sticking out past the left side of the transmission, but don't take it all the way out from under the car. Get out from under there.

6. Take off the left rear tire if you haven't done that yet and look in the wheelwell. You'll see the fill hole on the side of the transmission. Stick one end of the fuel hose in that hole.

7. Take the little cap off one quart of gear oil and snip the spout just enough that the oil will come out. You'll then have to remove the spout, take off the protective seal, and put the spout back on. Stick the spout in the end of the fuel hose and hold the bottle upside down. Cut a hole in the bottom of the bottle so the oil will drain into the transmission through the hose. It should be a small hole because you don't want it to go in quickly--this oil is very thick.

8. Repeat step 7 with the second quart of oil.

9. Repeat step 8 with the third quart but do not cut a hole in the bottle. You are going to squeeze the sides of the bottle to make oil go into the transmission. Not all of this bottle will fit. When the oil starts coming out of the hole, let it drain (now you know why you put the pan under the fill hole!) until it stops, then stick your finger in the hole. If the oil is level with the bottom of the hole, it's full.

10. Screw the plug back in, put the wheel back on and put the car on the ground. You're done.

Note: The official Volkswagen instructions say to get under the car with the oil container and put it straight into the transmission. They don't mention the hose. That's something I came up with because gear oil bottles are a different shape than they used to be, and they won't fit where they need to go now.