# Allison AT545 tranny oil and filter change.



## chips2002

Hello, 

I recently bought a 1995 Ford F800 with the Cummins 5.9 engine and Allison AT545. The truck has about 40,000 miles, and I wanted to change the tranny oil and the filter myself. I have no previous service record, but the truck was used by the city. So, I am thinking it has had some maintenance.

But first off, I have a few questions about the Allison AT545 transmission. I am new too big trucks and am not familiar with how the transmission handles.

The truck gets a lot of local and highway driving. When I drive in traffic, the temperature stays within 140 F to 160 F. But the thing that bugs me is when the truck comes to a stop. I don't know if it is the transmission or the brakes, but after downshifting to first (happens around 15mph), I feel this big jerk at around 13 mph. Is this normal?

Also, when I drive on the freeway, it barely stays within 60 mph. The top speed is around 65 mph on downhills. The engine rpm is at around 2600 rpm. The temperature is around 150 F. Is this all the AT could handle? Could I push it more? I am afraid it might decrease the transmission life if I drive over 60 mph constantly.

When driving the truck, how much throttle am I suppose to use? When shifting from first to second, I feel this big shock when I do not press the throttle too much (40% throttle). It seems like I get better shifts when I push the throttle about 75%. Is it better to kind of floor the truck?

Now back to the oil and filter change. Looking through the forum, I found that there is an internal and external (spin on) filter. It seems like their are mixed reviews on whether to change the internal filter or not. Some people say it is not worth the money and labor and is not going to affect the life of the tranny. Others say otherwise. What is the real deal? Should I change the internal filter and drop the pan? 

For external spin on filters, I was thinking about using Wix filters instead of the original Allison filter. Do you guys think it filter is alright? And for tranny fluid I was going to use the Cheveron Dextron oil is this alright. I see that some people are using C4 motor oil, what is the difference?


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