What would cause the oil to turn brown in a 2001 RX300 dealer replacement transmission-axle. This has happen in 10 weeks with 2500 miles of highway travel. There has been no overheating, trailer towing, or towing behind a motorhome. There has been two hard downshifts (2 to 1) while braking.

 

Welcome to CL. The only thing I can think of is the transmission cooler is clogged up from the debris from the old transmission. Sometimes a repeated trans failure can cause by the debris that the old trans gave away and collected inside the trans cooler.

Some to the RX the trans cooler is located as part of the radiator and some will have seperate trans cooler. You may need to get the trans cooler flush and I hope that will resolve your problem. Good luck.

 

so take it back to the dealer and have them fix it

if they already replaced the trans already with in 1 year. they will replace it again for free

 

Clogged system, bad A/T pump, bad ECU control of the valve body pressure.

 

And the torque converter, if they didn't replace it last time.

 

oil? Or are you saying the Red Genuine Toyota Tranny Fluid turned brown?

 

Yes, toy4two, Red/Pink transmission fluid will turn brown with overheating/transmission problems. The challenge is to find the root cause of the color change.