Auto transmission fluid operating temperature?

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Being able to measure and display the transmission fluid temperature in my auto box is one thing, but what is the normal operating temperature, and what is the upper temperature limit before pulling over to check/cool down? (2008 120 series V6 5 speed auto). I tow my 2 tonne van in 4th and Scangauge indicates that the engine is happier than towing in 5th (lower temperature, better fuel consumption, no gearbox hunting), and now with (soon to have) the ability to display ATF temp, I am keen to treat my gearbox with due respect with the aim of getting many more years out of it.

Appreciate any and all comments.

Cheers
Greg

[Lakers Lurker Find all posts View Profile Close Lakers]

From another thread in this forum (thanks to Tessa222z)...

"To answer my own question after some research; auto trans fluid should be at around the 80 deg C mark for normal operation. It needs to be over 70 deg for efficient operation and anything over 100 deg is a problem that will lead to seriously reduced auto life. Apparently even short spells over the normal range does damage to seals and to the oil itself. Now I need a big hill to see how hot mine gets. "

When Tezza222z wrote this he was referring to the auto box in his D4D, so I assume operating characteristics would be similar to a box in a 4L V6.

Cheers
Greg

[pjorek Advanced Member Find all posts View Profile Close pjorek]

this is very interesting, seems like those scangauge items are very useful indeed. So it will not only display engine temp but now Auto box temp too?

[Lakers Lurker Find all posts View Profile Close Lakers]

Hi pjorek, correct. Have a look here... http://scangauge.com.au/

I have been running a Scangauge in my 120 series Prado for over two years and it has been one of the better investments I have made. I have been hanging out for the automatic transmission fluid temperature codes (just released), but it looks like I need to upgrade my SG to v4.02+. This is not a problem, but just something I need to do.

Cheers
Greg