Allison Tranny Fluid

The early Allison transmissions used either Dexron or a c4 oil. The c4 oil was and is an engine oil.
When Allison went to Transyn (about 2006) they changed the seals to Viton. The use of a synthetic fluid in an older Allison can cause the seals to leak.
Chevron makes a Dexron 111 replacement fluid, MD3 which works well in older Allison transmissions.

There was a poster on here some time ago that was an ex Allison guy and he was able to answer all kinds of questions. I don't remember who it was, maybe someone does remember.

Thanks for the feedback. I had never heard of replacing tranny fluid with oil either.
But the sticker looks professional, and thought maybe Allison had "issues" with the tranny and the heavy rigs, requiring a heavier weight fluid.
i sell AMSOIL, so if I do change, it will be the AMSOIL product.
I will call Allison, and see what the deal is...

Keep in mind that synthetic lubricant upgrade to a transmission that has been in service, can and does result in leakage @ the seals. Better and cheaper to stay with original lube and change more often. Extended change intervals are a justification for syn oils, that isn't always a wise choice. I do use the Amzoil excuse for Transynd in my MD 3060 but that was starting with a fresh trans. Adequate cooling capacity is much more important and many chassis mfrs. are weak on that issue.

Recently had my Allison AT542 serviced by my diesel mechanic. Rather than the Transend, he recommended the Amsoil synthetic transmission fluid. His primary business is performance diesels.

Jon
92 Ultrastar 339TB
5.9 Cummins, MC16-FD Oshkosh

rkenly wrote:
i just bought a new to me coach.
it is a 1998 chassis
since im not home right now, dont know which allison it has.
however when i did my walk around, it has a big sticker that the dexron 2 fluid has been replaced with engine oil (15-40).
the dealer indicated that a lot of coaches did this to have smoother shifts?
is that because of dextron2 vs newer dextron 3, or transynd?
better to just leave it, or upgrade to transynd?

tia
>>>Rod<<<

Upgrade to Transynd. The transmission will shift smoother and run cooler.

As already stated I've never heard of replacing ATF with engine oil. I think I would have that changed before you do any traveling. Of course give Allison a call and see what they say. They have service centers around the country. Good luck and hope all works out.

rkenly wrote:
i just bought a new to me coach.
it is a 1998 chassis
since im not home right now, dont know which allison it has.
however when i did my walk around, it has a big sticker that the dexron 2 fluid has been replaced with engine oil (15-40).
the dealer indicated that a lot of coaches did this to have smoother shifts?
is that because of dextron2 vs newer dextron 3, or transynd?
better to just leave it, or upgrade to transynd?

tia
>>>Rod<<<

Well Sir, in all my mechanic life, I've NEVER heard of replacing ATF with engine oil, in any automatic trans, no matter who the maker of the trans was/is.

As for using Dexron II or, III, most Allison trannies came with Dexron II or III but, a few, were outfitted with Transynd, right from the factory. Mine is the Allison MH3000 and our coach is an '04 Itasca Horizon 36GD with the CAT C-7 330HP and like stated, the Allison MH3000. If I'm not mistaken, the Allison 2000 models came with Transynd. But, to be sure, dig up your vin and call your chassis maker and you'd probably be able to get info on what your coach was originally outfitted with.


Ours came with Dexron III and, a while ago, I did the complete change-over to Transynd. That was a bit expensive for the first change but it's supposed to last almost 100K before another trans fluid change.
Scott

I am down in Florida and visited an Allison Detroit Diesel dealer to determine the right fluids to put in my Allison transmission. Perhaps they can help you in your area. They told me they are a nationwide company.