I have a question for anyone that has a standard 6-speed transmission.
This weekend I was bringing a load of hay in and was in general pulling very heavy.
Gross wt was 29,380 lbs after two or so hours of steady driving I noticed that the trans temp gage was approaching 200 deg and would continue to climb to nearly 210 deg.

My question is
1) What is the max temp for a standard trans?
2) Would synthetic oil help to lower the temp?
3) What is the recommended synthetic oil?

 

Interesting topic. I just installed the add on coolers for a six speed and a temp sender on a customers truck. Neither of us were sure of what a "good" temp for a six speed is. We filled with the factory fluid.

 

bigfoot, I'm not going to be much help on this one since I don't have a tranny temp gauge, but I can tell you that after I put Royal Purple Synchromax in my NV, it shifts a lot smoother than with the stock fill. Supposedly the stock fill is a synthetic (Penzoil Synchromesh I think) and they call it a lifetime fill.

 

My dad has a tranny temp gauge and coolers and his rarely gets above 150 pullin a 24' enclosed featherlight trailer in the summer around the middle states/rockies. He has had coolers and gauge for several yrs now. Just guessing I would say you were still safe w/ ur temps.

 

I have a gauge on mine, I run loaded in the hot summer months at around 225. When im empty is 145 or so. In the colder month like now loaded is 195 , so i would say you are just fine with what you are getting.
This is with the pennzoil stuff, I change mine evry 20,000 miles.
Hope this helps

 

I ran Redline MTL in my 03 6 speed, and it would get up to 195-200 pulling in the mountains, or cranking up the twins alot. The tranny actually will run slightly hotter than the rear axle. I had one gauge with a momentary button next to it, to switch between the tranny/axle.

 

Thanks for the help. I was a little worried that the temp was too high. I know that I was towing real heavy and also it was a 500-mile tow but things just did not look right to me.