Synthetic Transmission Fluid?

[Lin]

It looks like we are soon to be finished with installing my Allison 647.  Are there any opinions (silly question) regarding whether to go with standard of synthetic fluid.  Is Amsoil the equal of Transynd?

[johns4104s]

Lin,

I was having hard changes from 1st to 2nd and back down to 1st. I fellow bus nut recommended I change to Hyrotech from Dallas Texas. It cost me $300 to change. But the shifting is 90% better. They test a sample annually and tell you wen to change it. They specialise in School bus fleets were they are getting 500.000 to 750,000 miles between changes.

Let me know if you need any more information

John

[luvrbus]

John, better check your Allison manual on oil change intervals using synthetics no 500,000 miles 

Lin, a good C-4 15/40 oil makes the Allison shift smooth also but it's your dime



good luck

[Lin]

Clifford,

Were it only a dime!  You must have a great supplier.

[johns4104s]

Clifford,

I hope my Allison tranny See's me out and it won't be 500.000 miles 60 or 70 maybe?
The Hyrotech oil I used just took a lot of the thud out of the 1st to 2ND change.

John

[bottomacher]

Do Allison transmissions have a torque converter drain plug? I have always been told not to mix synthyetic and regular transmission fluid, so I always have to wait until I can remove the converter.















i

[luvrbus]

No they do not have a drain on the converter you need to change the synthetic oil twice unless starting with fresh transmission 800 bucks worth of fluid ?
I use Cat Power Shift oil in mine 12 bucks a gallon and if it is good enough for a 30,000 dollar Cat transmission a 3,000 dollar Allison is a strole in the park.



good luck

[Lin]

Here is a link to Allison approved C4 oils.

https://fdlrd.swri.org/Allison/ApprovedFluidsList.aspx?Id=1

Clifford--There is a Powershift transmission oil that is a synthetic made by Amsoil.  I don't think that is the one you refer to.  I assume it is one specifically recommended by Caterpillar for the Power Shift Transmission.  Do you know the brand name and manufacturer?

[buswarrior]

Busnuts report that their transmissions run somewhere 10 degrees cooler with Synthetic versus regular tranny fluid.

There is also a bit of a conspiracy regarding Transynd.

As I understand it, the test rig to prove any other fluid to the standards was destroyed, and the specs to build one are secret...

So, sole supplier, no possible future competitors can test to show equivalency...

A friend of mine is an Amsoil dealer, and when the time comes, I'll convert to theirs.

happy coaching!
buswarrior

[edroelle]

Since the 647 is lighter duty than the 740, and probably at its limit, you aught to use the Transynd.  Good insurance.

The same recommendation holds for the B500.  

The Transynd can take higher loads and temperatures without the fluid breaking down and losing lubricity.  

Ed Roelle
Flint, MI

[Lin]

By the way, how much oil does the 647 take?

[Chopper Scott]

I know that you cannot mix synthetic brake fluids with normal brake fluid but I am not aware that mixing dyno with synthetic tranny fluid is of any concern. You can buy 50/50 mixtures of engine oil right off the shelf. I doubt anyone would recover their initial expense by going to synthetic but I do know that going to synthetic in my motorcycles made a very noticeable difference in shifting. Also I have a MC 7 that is marginal in the cooling department with the Allison. Any step that helps with the cooling is of interest to me!!

[1960eagle]

transynd has friction modifier additives that reduce clutch plate shutter.maybe something to consider? also many shops now have total flush systems that will remove all trans fliud and replace with new.besure however that it is a non pressured machine.

[belfert]

The reason I converted my B500 to Transynd is because it can stay in the tranny for 4 years.  Allison recommends the dino stuff be changed every year or 25,000 miles.

I have yet to find any of the TES 295 fluids that are also approved for 4 years, but I haven't looked real hard yet.

[Lin]

I Allison says to change standard fluid at 25000 miles/12 months, Transynd at 50000 miles/24 months, and a mixture of both at 50000/24 months.  They define mixture as the quantity of oil left while changing to Transynd.  Could be they just want to encourage you to buy their stuff, I guess.