Anyone who owns a 4WD Toyota and has dealt with the drain and fill plugs on the IFS front diff knows that they generally suck. They use either a 10mm or 12mm hex key, and that can be a problem for many reasons:
- The recess that the key fits into can easily get filled up with crud.
- If the recess isn't cleaned and the hex key doesn't fully seat, it's easy to round over.
- Hex key's aren't generally all that long, so it's hard to get the leverage needed to loosen the plugs.
- The plugs can get extremely tight, making it hard to loosen with a hex key.
There are ways around some of these shortcomings of course - you can fully clean out the recess, you can use a hammer to rap on the drain plug a few times before removing it, and you can try using a hex impact socket. But in all those cases, we're really just working around something that could be better anyway.
I don't know why Toyota did this to us all, but some number of years ago, they realized how terrible it was. And so they made new plugs that had traditional 14mm hex bolt heads. All was going to be right in the world, once again. Except that they decided they'd limit these new plugs to Lexus vehicles, continuing to install the hex key-style on Toyotas.
Luckily for us Toyota owners, the Lexus plugs fit our differentials as well. And today, I'm making my life just a little less painful by switching out the drain plug for the front diff - since I'm changing the oil anyway. The process is easy.
- Loosen the fill plug at the top-front of the front diff. Always loosen the fill plug first, to make sure you'll be able to refill the diff after you drain it.
- Loosen and remove the drain plug at the left (driver)-side-bottom of the front diff. Drain the oil into a catch can.
- Throw the horrible drain plug in some bin somewhere.
- Replace the crush washers on both the fill and drain plugs with with new crush washers.
- Replace the drain plug with the Lexus OEM version (90341-24016). This plug uses a standard 14mm socket.
- Refill the diff with some new diff oil (I like Lucas 80W-90). Buy it by the gallon to save a few bucks.
- Reinstall the fill plug.
That's it. Your future self will thank you.
Update: April 2021
Well, I finally found the Lexus equivalent for the fill plug as well. It uses a 14mm head, and like the drain plug, eliminates the risk of rounding out the hole. Pick up your own here: Lexus Front Diff Fill Plug (90341-18060)