V730 trans

[JLL]

I have a V730 trans in my 4106.  The other day I was talking to a fellow that had a high dollar MH. He said he changed to Synthetic trans oil and it now runs cooler. 
Any comments?
My questions are
if I change  what weight should I use?    What brand?
What is the oil  capacity.

[TomC]

The synthetic oil that is recommended by Allison and now filled at the factory brand new is Castrol Transynd.  In order to do a complete oil change you need to change the oil twice.  Change the oil once with oil filter, run the bus at least 1000 miles, then change the oil and filter again.  It takes the two oil changes to get the old oil out and replace with the new synthetic.  Be ready for expensive-about $45.00 per gallon and I believe 8 gallons worth! 
Personally- I installed an auxiliary trans cooler on my V730 with an electric fan.  It is plumbed on the hot side between the trans and the bus trans cooler, so the auxiliary cooler takes most of the heat out before even reaching the shell cooler.  Some even take the shell cooler off and put a big Hayden transcooler in front of the radiator.  If you do the electric fan auxiliary cooler, make sure you wire the fan to pull air from the engine compartment to the outside.  This sounds like in reverse, but with the pressure of the big engine driven radiator fan, that little electric fan can't overcome the pressure.  So instead of fighting it, just go with the flow-and that's from the engine compartment to the outside.  I also put a thermostat on the auxiliary cooler-on the outlet side, so when the cooler gets over 180, the fan comes on.  Good Luck, TomC

[happycamperbrat]

Okay, color me dumb! For someone who is trying to learn mechanics, please explain to me why the tranny cant just be topped off with the synthetic and mixed with the old? Why is it so important to have the old tranny fluid out before adding the new synthetic?

[steve wardwell]

huh? .....happyCB..... to help change trany temp one would need to CHANGE THE OIL to synthetic.  Not mix old and new into a stew of wasted $s with little or no gain.... Synthetic is more slippery than petroleum oil hence it will run with less Resistance = less heat. By the way if you have leaks synthetic will leak even more because it seeks to fill even smaller crevasses than reg. oil.

[happycamperbrat]

Okay, got it thanks!! I was just trying to make sure it was okay to mix them. Around $1000 to clear out the old tranny fluid and put in the new just sounded kinda steep to me. I could see gradually doing it over a period of time though. And I think I will start buying the synthetic. Thank you again!

[steve wardwell]

The only complaint I've ever heard against synthetic was it can find leaks in formrely "tight engines/tranys...Well, than again theres  the $........s........

[TomC]

Personally don't think it is worth the money.  If you're full timing it like Sean, then OK.  But if you're only putting on around 5,000miles a year, it won't ever pay for itself.  Good Luck, TomC

[Melbo]

I don't know if this applies to your transmission but on my ZF they recommend changing oil every year even if there are no miles driven -- just preventative maintenance -- the shop manager told me that oil was the cheapest thing you ever put in a transmission.

He said good quality oil was all that was necessary so as another opinion skip the synthetic oil

Melbo