Recently I was doing some routine maintenance on my 1999 Toyota Avalon XLS and when I was checking the 95k mileage procedures one of the items which caught my eye was replacing the differential fluid.

Earlier this year I changed my transmission fluid as a fairly straight forward procedure (since the plug was right under the front of the car) however the Chilton manual I used only showed a picture of the V4 underbody vs. the V6, so when I went looking for the differential fluid I was left with the impression that the V6 didn't have a separate tank.

When I saw the differential matter again, I looked deeper into the issue and one of my relatives stumbled on a diagram showing that my 1999 Toyota Avalon XLS has the differential fluid plug right above the catalytic converter and that I'd need to remove that to change the fluid.

Is there a logical reason for this, or is this a misreading of the pictures? As messing with the catalytic converter is a risky deal, I'm sure this is an error, but if so, I'm having trouble finding where the differential tank is.

Currently I'll say that on forums I've seen a mix of people saying the XLS has a separate tank whereas some say it doesn't, but the Chilton book I use even says the V6 uses ATF Fluid in the differential tank, but for some reason they don't show the location, which is why I've been stumped.

1 Answer 1


If you car is well used in harsh climates, the catalytic converter may be hard to remove. Are the bolts all rusty? Try loosening one--will it budge easily? Exhaust parts tend to be annoying to remove if the car is old enough.

Otherwise, if it's clean and comes off easily there's no other risk in messing with the cat. This is not unheard of on front wheel drive cars. Just be sure to disconnect any oxygen sensors attached to it.

You should be able to trace the fluid lines from the differential to the fluid reservoir, if I read that part correctly. If you can get your eyes around anything in the way, that is.

  • Thanks very much for the answer! It's nice to have some closure on the question.
    – theonlylos
    Jul 12, 2012 at 19:10

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