I have a 2004 Mercury Marauder with 31,000 miles on it and a 1983 Chevrolet El Camino with 371,000 miles on it.
I have done an auto-rx application in both transmissions, the Marauder has an external trans cooler whereas the El Camino does not have one.
I use Amsoil ATF in both transmissions and I have taken a pan reading with an infrared gun on both cars. On the El Camino I can aim the infrared gun at the torque converter since I took the flywheel cover off a few years ago.
I took temperature readings after driving both cars for about an hour in 90 degree weather.
The El Camino had a pan temperature of about 95 degrees whereas the Marauder had a pan temperature of 92 degrees.
The torque converter temperature on the El Camino had a temperature reading of 150 degrees.
Before doing auto-rx in the Marauder I had a pan temperature reading of 135 degrees, I replaced the Mercon V trans fluid which is semi-synthetic too Amsoil ATF which is 100% synthetic, I am guessing that the lower pan temperature reading on the Marauder is probably due too the synthetic trans fluid and auto-rx, so I will give auto-rx 50% credit and the Amsoil ATF another 50% credit.
My other feeling is that on both cars since the transmission is clean inside that the trans fluid can get to every part of the transmission and that is why it is running cooler.
AUTO-RX is an amazing product if it can clean my El Camino's transmission that has many more miles than my Marauder and the pan temps are almost the same.
It is important to remember that heat is the number 1 killer of transmissions, and that auto-rx is such a great product in cleaning a transmission that you may not need an external trans cooler.
The external trans cooler on my Marauder is almost as wide as my radiator and about half as tall as my radiator.
My infrared gun proves that auto-rx works in cleaning transmissions, if the transmission is clean than the temperature of the fluid will be lower than a transmission that is dirty.
There were some people who thought I was crazy too do an application of auto-rx on my Marauder's transmission at 29,000 miles. But, when I changed the fluid out it was slightly dark, like a dark burgundy color. Most guys I talked with said that when they changed the trans fluid at 30,000 miles on there Marauder's that the trans fluid was a bright red color. I drive the car very conservatively, it's not like I drive it hard.
Frank was right when he said that junk builds up in your trans and engine within the 1st 25,000 miles.
Before doing auto-rx in the Marauder's transmission my El Camino;s transmission shifted better, now they are both equal in shifting quality.
Why not just install a temp guage? I have one for the trans and one for the oil. It's a F-150 and the trans cooler lines go thru the radiator so it warms the oil and there's a bypass to help keep it cool. I put a bigger trans cooler on and the electric fan never needs to come on.
The problem with a temp gauge is that the sensor is either mounted in the cooler line or trans pan. My readings with an infrared gun tell me the torque converter is the hottest part of the transmission.
The torque converters of any automatic transmission will be the hottest part, atleast during city driving or on transmissions with no torque converter lock-up clutch. The fluid is transferring energy from the engine to the driveshaft, therefore it is under a lot of pressure and heats up quickly.
And even though the internal temperature sensor is on the cold side of the coolant, it will still give an accurate indication of what the ATF temps are like and you can tell when it is hotter than normal indicating a problem (or a really hot day at the track).
I use ScanXL on my laptop to read my OBD-II and Ford PIDs from my ECU. I monitor the ATF temp using that and it stays around 165-175*F under all driving conditions for me once warmed up. I replaced the ATF a year ago after an Auto-Rx treatment with Mercon V semi-synthetic and is still clean as when I put it in.
I believe that using the infrared sensor, while can be useful, can not give a good indication of the ATF temps as compared to different car models. Keep in mind different materials, thicknesses, etc. between your Marauder and the El Camino transmission cases.
In addition, the Marauder and most cars with transmission coolers (including my 2000 Grand Marquis) will maintain a pretty standard temp even if the ATF is somewhat worn out. The transmission cooler has a thermostat just like the coolant system which should keep the ATF around 170*F. It may differ +/-10* but that still gives a good buffer before the ATF gets too hot to function properly and burn.
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2000 Mercury Grand Marquis LS [ pictures | videos ] Dual Flowmaster Delta 40s / J-Mod / PI Intake Manifold / Marauder Air Box / 80mm MAF CVPI Zip Tube / Ported & Polished Plenum / BBK 70mm / 93 Octane Tune / Steeda Underdrive Pulleys
RichG, I agree with everything you have said and I realize the infrared gun is not 100% accurate.
I was looking at a trans temp gauge that mounted the sensor in the trans cooler lines, with an infrared gun the temps at both cooler lines were much lower than the torque converter temp on my El Camino.
Since the Marauder is newer and the fluid has been changed as well as there is an external automatic transmission cooler I am less worried about the trans temp.
