Allison HT748 Rotella 30W ?

[NeoplanAN440]

anyone running Rotella 30W on their Allison ht transmission ??

having some internal leak problems  (slipping reverse), so im trying if going from 15w40 to 30W will buy me some more miles before i drop the transmission!!!

[Sean]

Might help, especially if the problem is a partial obstruction in one of the passages.  In which case, even better would be to drain and refill with Dexron-III transmission fluid.

FWIW, we improved the performance and lowered the temperature of our 748 by switching from Dexron to TranSynd, but that's very spendy at ~$40 per gallon.  I would try the ATF and see if it improves.

We've had some hard shifts ever since we re-enabled our VSS, and your connector findings in the other thread has me wondering if we maybe also have a loose wire.

-Sean
http://OurOdyssey.BlogSpot.com

[Marcus]

I put amsoil synthetic transmission fluid in my 740. It works great and lowered temp 10 degrees.

[NeoplanAN440]

the reason we want to go to a higher grade is,that the transmission works fine when cold.
as soon as its hot, more then 50 miles of driving, the reverse slipping begins.
im thinking that i have a leaking valve body or clutch pack.
so switching to thinner atf should worsen my problems !  i guess

as for the connector  !!!

yes ,i never thought  that these wiring issues will be undetected by the ecu, and still  mess up the whole tranny performance! when we started troubleshooting, we blamed it all on the 12v powersupply and how the neoplan circuits are designed. finding now that only one bad connector is the culprint for all of it!!!

[NeoplanAN440]

that everybody understands,

im only trying to get through this summer with this engine tranny combo.
i have a replacement cummins l10 with newly tranny sitting,as my winter repower project!!!
we still have to do a couple of trips, about 10k worth of driving with a mildly loaded (under 15k) trailer.
and im just trying to find out my numbers,if i can do it.
so far i streched it for the first 1500 miles, and im ready to play more poker on this!

[RickB]

I switched to rotella 15-40 in my 754 2nd geart start transmission that was very rarely and only under extreme situations (muddy ground that the tires sink into or Atlanta stoplights of which some are easily 10% grade dead start takeoffs) and it completely cured my issues but I don't know if switching to a single weight oil will help you if you are already running 15-40. I know that you would need to be vigilant about letting the transmission warm up if you find yourself on a 30-40 degree morning. You could also have the transmission pressure checked at an allison shop to see if you are really close to a serious failure. They have guidelines of the pressure needed to fully engage the clutch packs.
I would personally be a bit concerned about it breaking 1000 miles from home and the towing/repair bill you would be facing to get your bus home with a tranny that you plan to replace.

Let us know how it works out for you.

[NeoplanAN440]

i know about watching my cold trans temp before starting. good thing,that we mostly dont get below 50 here in new mexico. i also have my webasto plumbed into the engine circuit,so when my shower is ready, my engine is sitting at 160 before i start it!

i will look into getting the pressure tested on that clutch! problem is that they have to get me in when i come in from the interstate. as soon as im cooling down, everything is normal again.

thanks for any hint

[stevet903]

From the Allison Operators Manual:

....  Use C-4 SAE 30 where ambient temperatures are above 85F (30C).

Rotella 30W is also rated as a C-4 oil, so you should be good to go!!

      http://www.shellusserver.com/products/pdf/RotellaTSG.pdf

[luvrbus]

You need to check the temps at the torque converter and the sump your gauge reads the torque converter temp sounds like the torque converter going south ,check that pressure also that's were I would start 



good luck