Allison transmission fluid change interval.

Change it now. You have no idea how the previous owner treated the engine/transmission. If you also go synthetic, follow the appropriate guidelines.

johnhicks wrote:
Have the fluid tested.

Agree. If it tests good, and continues to test good, it is good until it does not meet the parameters on the test sheet. Here's who I use every year: https://jglubricantservices.com/

I have the same RV just a little newer and it charges everything when driving. Has almost 100K on it and just replaced the alternator and all the batteries. 3rd time replacing batteries.

bgum wrote:
And be aware that it takes 2 changes of transynd before you can use the duty cycle of synthetic rather than generic transmission fluid.

Correct.

If this is the first synthetic change, per Allison, the change interval remains the same as for non-synthetic oil.

And be aware that it takes 2 changes of transynd before you can use the duty cycle of synthetic rather than generic transmission fluid.

Assuming this is an Allison 3000 series, most cost effective is:

5 gallon pail of Allison 668 Transynd. That will leave you about 1 quart left over.

An Allison filter kit-- take your transmission model/serial number in with you to get the correct filters/gaskets-- kit is complete. The model/serial number is on a tag on the driver's side of the transmission.

About the only thing you need is a bucket and an inch-pound torque wrench. Easy DYI job.

Have the fluid tested.