Transmission oil and filters when to change ?

If it's a Allison 3000 or 4000 transmission and you have Transynd then it's 5 years or unless your oil monitor system indicates otherwise. You should be able to check the following off the Allison transmission selector key pad.

OL - oil level ( two minute delay after stopping in idle engine on) press up and down arrows at the same time

OM - maintenance required (change) - press arrow key again while in above mode and it will scroll to one of the following and indicate, "OK" or a issue

FM - filter maintenance

TM - maintenance

If you read your owners manual it's all stated. If not your can download a Allison manual on-line by doing a search.

If you see a wrench in that display you have something needing to be addressed. You really need to get a manual

I would suggest you look in your Allison transmission manual. It will give you the change intervals. I seem to recall that they recommend changing the fluid around 10,000 miles, and then after that it is a long interval: 50,000 or 100,000 miles.

Hmm, seems I posted this at the same time Brett did.

Ed Headington

Your Allison owners manual (also available online from Allison) give their recommendations for both fluid and filter changes.

Assume you have Transynd fluid-- you need to verify, as its change recommendations are quite a lot longer than with Dexron.