Extreme cold weather Synthetic ?

[Nineforever]

Schould we change to synthetic oil in manual transmission and diffrential if were operating in - 35 weather 50 % of the time , we never bothered to use synthetic oil in the automatic MC9 never seemed to be a issue , but the 102c with a 6 speed once you have been out on the open road transmission very stiff hard to shift . Once your back of the hyway in town lower speeds warms up easy to shift gears .
Engine running 185 degres
Any insight appreciated
Dave

[luvrbus]

What weight oil are you running both the Fuller and Spicer 6 speeds take 30,40 and 50w engine oil

[wg4t50]

Had great luck with #50 Synthetic in the RTO910, loved it, no leaks and no issues. Coldest ever had it into was -10f, again no issues.
Dave

[Oonrahnjay]

  Had great luck with #50 Synthetic in the RTO910, loved it, no leaks and no issues. Coldest ever had it into was -10f, again no issues.     Dave   

      If I ever drive my bus into any weather that's colder than 50 degrees above that, just shoot me, OK??

[Nineforever]

Were using sae 30 in the engine and sae 40 in the transmission not sure whats in the diff

[TomC]

I know that Eaton makes transmission coolers that tie into the coolant system of the engine. The advantage to this is that during winter the cooler will actually warm up the transmission and keep it up at operating temp on a very cold drive. This also makes for more consistant wear pattern since extreme swings in temperature are not good for bearings. Then with the radiator powered transmission cooler, if you have a block heater, your transmission will be warm also when starting.

I have an electric block heater on my truck. When I was driving in winter, I also had a 120vac boiler circulating pump (magnetic pump so there were no seals to leak) to circulated the radiator coolant through both the primary Diesel fuel tank and the fresh water tank (Arctic Fox). When it was cold, the gasoline powered Onan 6.5 air cooled ran all the time when stopped since I had electric heat. The hot air from that just blowed straight down. I took a piece of cardboard and created a "duct" to blow the hot air back up towards to exposed water line and the transmission. Never had problems with shifting the transmission. Good Luck, TomC

[belfert]

Don't most Allison automatics have a water to oil transmission cooler?  I know mine does and I have seen them on other makes of buses with the B500 transmission.  My transmission temp and engine temp will go up and down in unison since they both use the same cooling system.

[TomC]

Plus with an Allison transmission the automatic hydraulic fluid is more like a 10 weight oil that rarely gets thick (at least above zero).  Good Luck, TomC