Transmission Service

Thanks, Bob. I have always changed my spin-on filter every other oil change also. One of the Service Managers I talked to when I first bought the truck recommended it.

I have an 05' and Allison does not reccommend a flush. If you have an Allison dealer near you you can buy Transynd for alittle over $30 a gallon and a spin on filter for about $9.00. Allison has a drain plug so it's no problem to change. You don't drop the pan for the internal filter unless you are doing an overhaul. Drive for 10,000 miles and repeat and Allison considers this to be a complete switchover to synthetic. You will notice smoother shifts and lower temps. It takes alittle over two gallons for the exchange and fill the spin on before you put it on. I change my spin on every other oil change. Cheap insurance for an expensive transmission. This is just what I do. I'm not saying it's by the book, but from being on the diesel forums it is usually an accepted maintainence schedule.

I dont know about any other than Ford but places like Jiffy Lube can also do it right providing they have the Transmission Fluid Exchange machine. This is a machine (looks something like this: ) that connects to each line from the tranny to the cooler at the radiator. It works on a displacement process.

There is a baffle at the top when the unit if full and ready to use. As this runs the baffle moves down top contains old fluid and bottom drains into vehicle.

The vehicle motor does the work and must be running for the process to work. One line draws out the fluid and the other replaces with new fluid. It is the best way to fully replace ALL the fluid including the bell housing, pump and reservoir/pan. Talk to them and ask to see their pump - and watch if they will allow you. Mine was about $80.00.

Thanks, mtofel1. The manual says to replace fluid and filter at 50,000 miles under normal driving conditions. I have 54,000. I've read posts on here before about the pros and cons and, like you, came away more confused than when I started. I figure if I call the dealer he's going to say, "Sure it needs it. C'mon in." :) I don't believe my manual says anything about flushing. I guess what I was hoping for was some real world experience from the forum. I'm certainly in no hurry to spend $200.00 + if it isn't absolutely necessary.

I think I paid $200 at the Chevy dealer a few years back. Watch out, this thread is undoubtedly going to digress into a back and forth about the pros/cons of flush vs drain/fill. Last time this went around it was somewhere around the 15th page that I realized there is really no perfect answer.

If I remember right GMC/Chevy says every 40K do a power flush and Alison says don't ever do a power flush. The "data" that I'm remembering is about 4/5 years old so this may have changed.

I personally did the power flush at 40K to keep the warranty gods happy and have just done drain/fills along with changing the spin-on filters (do the new trucks even have these?). I'm at 130K on my bone stock LBZ and the tranny has been absolutely flawless so I don't plan on changing anything in my methodology. My fluid is still bright purple and clean everytime I check it or do a drain.

My advice is to listen to the opinions, do some research and decide how you want to proceed.

On edit: oops.... I just assumed you have a new truck. I see your profile says it's an 05 so I'd really do some research before you let the dealer power flush. I personally would never do it on a tranny that old but that's just me.