Allison transmissions are the heavy duty beasts that you'll typically find in a class A motorhome. They come in a large range of sizes, from the Allison 1000 up through the Allison 4000 series. Each model is capable of handling more torque and horsepower so you'll find that whichever one you happen to have will be best suited for your engine and GVW rating. For more detailed information on the various ratings please check out the Allison Transmission Specifications document on this website.
There are a few distinct differences in servicing the various models. The Allison 1000 series, commonly used in the smaller Workhorse chassis uses a simple spin-on oil filter and doesn't hold as much oil as the larger 3000 series used in most diesel pushers. The larger transmissions also use insertable cartridge style filters as well as a fairly hefty oil supply. For exact instructions on servicing your Allison transmission please be sure to refer to your owners manual to ensure that you are getting the exact requirements for your specific year and model of transmission.
Do note that an initial transmission filter change is required on all Allison transmissions at 5,000 miles. On the larger Allison 3000 series there are two filters, a primary and a secondary. It is only necessary to change the primary filter at this initial service. Allison requires this to keep from voiding your warranty and it's intended to remove any contaminants that have entered the system during manufacturing or during the initial break-in period. After that you can continue on your regular scheduled service intervals.
There's lots on misinformation floating around as to when to service your transmission. Rather than take this advice why not go right to the source? Allison has a service interval calculator right on their website. You just select your transmission model, answer a few questions, and they'll tell you exactly what is required. It's the best source of information and you can find it by selecting the following link:
There is a difference in service intervals, depending upon whether or not you are running the generic Dexron style C-4 fluid or the synthetic Transynd fluid. Allison recently opened up the requirements to allow some other synthetic fluids to be used. However, not all are approved. They must meet Allison's TES-295 specifications in order to be listed on the approved list. Information on these fluids can be found at the Approved Allison TES-295 Fluids link. Freightliner began installing Transynd fluid in their chassis as of 1/2/04. If you have this fluid you can use the extended service intervals. There should be a decal near the transmission dipstick tube stating to only fill with Transynd if this is the case.
Servicing an Allison 1000 with a spin-on filter isn't that much different than changing oil on your car's engine. If you have an Allison 3000 it's a bit more involved but it's really not that bad. The following procedure to change fluid or filters on an Allison 3000 transmission was submitted by Herb Peterson:
TRANSMISSION FLUID CHANGE PROCEDURES:
Allison does have a streaming web video on their website that will train you in the proper use and care for your motorhome's Allison transmission. If you want to view this video it's in the lower-right hand corner of that webpage at www.allisontransmission.com/product/commercialtransmissions/recreational/index.jsp or else you can select the following link:
Submitted by Mike Sundberg and Mark Quasius - 3/29/06