View Full Version : 5MT transmissions NEED an oil cooler when driven hard!
Hobby Racer
10-05-2018, 10:15 AM
I have a temperature sensor inserted in the fill plug of my 5MT and wanted to share some data from my last track day at Watkins Glen race track. After a 20 minute session of hot laps the ending oil temperature was 280 degrees and the ambient temps were only in the high 60's! At those temperatures the oil is definitely going to break down and not provide the kind of lubrication needed for the transmission.
Normally I run a transmission cooler (https://thefactoryfiveforum.com/showthread.php?23199-John-s-EZ36R-H6-818R-Build&p=313246&viewfull=1#post313246) but I turned off the pump for this one session to see how hot the trans oil gets. I thought maybe I did not need the cooler as I normally do not see temps over 180 degrees with the cooler on. I guess its doing its job ;)
Just thought I would share for those not monitoring transmission oil temps and not running a cooler.
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EODTech87
10-05-2018, 08:10 PM
I'm actually kinda glad this is the case. I went ahead and setup my transmission to run a oil cooler just in case and now I know it wasn't a waste of time and money.
aseecobra
10-05-2018, 08:52 PM
Hobby,
Are you using ATF or a manual trans fluid?
Hobby Racer
10-06-2018, 08:45 AM
Hobby,
Are you using ATF or a manual trans fluid?
Red Line 75W90 NS GL-5 gear oil. You should not use ATF in the 5MT, its bad for the ring and pinion gears and not great for the bearings.
Sgt.Gator
10-08-2018, 11:11 AM
Good post with real data. Do you have a link to your solution? Are you using the LGT tranny or WRX?
Mitch Wright
10-08-2018, 12:26 PM
I don't have a trans cooler, haven't felt the need. But now I am curious on what the temp actually is so I just ordered a sensor and cable to log on my AIM MXL.
Hobby Racer
10-08-2018, 02:57 PM
Good post with real data. Do you have a link to your solution? Are you using the LGT tranny or WRX?
Here is a link to the start of the cooler posts (https://thefactoryfiveforum.com/showthread.php?23199-John-s-EZ36R-H6-818R-Build&p=313246&viewfull=1#post313246) from my build thread. I'm using an 06 WRX transmission, from what I've read on nasioc its the same strength as the LGT transmission. I have also just recently swapped out the tall 5th gear for a close ration 5th and love it!
I don't have a trans cooler, haven't felt the need. But now I am curious on what the temp actually is so I just ordered a sensor and cable to log on my AIM MXL.
Please post back with data points. It will be good to see if you are getting similar temps.
Rob T
10-08-2018, 08:39 PM
I have a 5 MT from a Legacy. I have not run a sensor, but have used an IR gauge after some 25 minute sessions and recorded about 250 on the case. That was before I began running Motul 300LS 75W90. According to Motul, it is a full synthetic Esther based lubricant and can handle some of those high temps. I am interested in the oil cooler ideas for the 5MT as well. Things seemed a little cooler the last time out with 222F and 210F after some 20 minute sessions.
Mitch Wright
10-09-2018, 08:30 AM
I am not concerned with 250+ temps using synthetic gear oil and I do change the gear oil a few times a season. But John has my curiosity peaked so I want to know what the temp is and will be interesting to compare notes. I haven't run a session more than 35 minutes and the longest race I will run with the car would 45 minutes and still trying to find place to make the lighter.
Sgt.Gator
10-09-2018, 04:09 PM
I have a 5 MT from a Legacy. I have not run a sensor, but have used an IR gauge after some 25 minute sessions and recorded about 250 on the case. That was before I began running Motul 300LS 75W90. According to Motul, it is a full synthetic Esther based lubricant and can handle some of those high temps. I am interested in the oil cooler ideas for the 5MT as well. Things seemed a little cooler the last time out with 222F and 210F after some 20 minute sessions.
It's fairly easy to do a LGT tranny for a cooler because you can use the speedo port, there is no speedo gear inside a LGT tranny like on a WRX 5 speed. You need two welded up steel AN fittings, one for the speedo port (return from pump/cooler) and one out the bottom of the drain fitting (to the pump / cooler). I've posted pics in the forum on this before, but here they are:
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