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Discussion Starter · #1 ·
at 109k on my 2003 i'm 3/4 thru a 16 quart drain/fill cycle using castrol high mileage atf. since i've gotten my scan gauge i notice that stop and go driving with intake air around 87 gets me an atf temp between 160-170 very easily.

does regular atf, as oppossed to synthetic have a higher running temp or should i be worrying more about packing for the next trip south?
 

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they both run same temp...synthetic just withstands higher/lower temperatures better (theoretically) than standard, and why arent you using the recommended tranny fluid?
 

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175F is the optimum *sweetspot" operating temperature for DEX III ATF in the transmission. At that temperature your tranny will work the best and the fluid will last the longest.
 

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Any previous maintenance?

I wouldn't call 170 a sweet spot. Its too hot for 'normal' non-aggressive driving.

Check the flow through the ATF coolers. Something might be clogged.
 

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my trans on my 01 tundra access cab stayed around 135 during normal driving but if i was pushing the truck hard i never saw over 160.
 

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Discussion Starter · #9 ·
Any previous maintenance?

I wouldn't call 170 a sweet spot. Its too hot for 'normal' non-aggressive driving.

Check the flow through the ATF coolers. Something might be clogged.
any help with a how-to?

edit: today driving around town up to 202 water temp, 132 intake air temp, atf temp up to 182. should i be trippin?
 

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Discussion Starter · #11 ·
i got the codes from another thread and they seem to work:

Every so soften I get mad about the folks at Linear Logic stringing us along and failing to crack the ScanGauge codes for trans temp for our trucks. It motivates me to root around the web and see if I can find any potential clue. The fan base is surely large enough! Today I came across this set of XGauge codes.

TXD: 686AF101B4
RXF: 044105B40000
RXD: 2808
MTH: 00090005FFD8

<http://www.fjcruiserforums.com/forums/1450732-post14.html>

So I just tried it on my 02 Tundra 4.7L and it looks promising. My truck set in the garage all day today. It was about 90F outside. The initial reading was 78. It didn't change so I held the brake, shifted into D and revved 2000 rpm (convert stall) maybe 15-20 seconds then the numbers started to climb. I shifted back into P and idled for another minute or so while the numbers inched up to 111 peak. After the better part of another minute the number started sinking back down. This looks promising indeed.

Cheers
Kamper Bob


you'll need to program your scangauge with the codes.
 

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Any previous maintenance?

I wouldn't call 170 a sweet spot. Its too hot for 'normal' non-aggressive driving.

Check the flow through the ATF coolers. Something might be clogged.
Dexron III ATF was formulated and designed to operate best at 175F. If that's what your tranny runs at most of the time, you will have no problems. It is also important for the additive package to be effective at around this temperature. Many additives used are actually heat activated in order to be most effective. But too much heat can be detrimental to the base oils of the ATF, the tranny seals, clutches, and various metals. Here is an easy to read link about ATF servicing:

How often should the automatic transmission fluid... — Yahoo! Autos

To me, these ScanGauge readings that people are using seem suspect. They don't seem to jive with any other truck readings that I've seen using OEM computer or factory installed gauge readings for transmission temps. A good way to check the accuracy would be to leave the truck outside on a cloudy day and see if the Scangauge readings follow the outside air temp. If they aren't exact, they should be very close to it. My daughter's Avalanche seems to do this perfectly with her factory installed ATF digital temp readings.
 
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