Well I've had my '03 LB7 for about 2 years now and clocked about 30K miles to put it just over 200K total. The vast majority of my miles were highway since i have a Prius for my daily driver around town and usually only use the truck for longer trips. I just added a Lance camper and beefed up my rear suspension with Roadactive coil springs over the leaf springs. I'm preparing for a 6,000 mile trip this summer, crossing the continental divide twice so going to be working the tranny quite a bit more than it's ever seen to date.
The prior owner was pretty good about maintenance and mostly took it in to shops so the CarFax record is pretty robust and I was able to contact the shop who did the last tranny service in 2018 only about 40,000 miles ago. Sadly it turns out they put Dexrox VI in it, which was not what I was hoping to learn.
In any event I've already bought an Allison spin on filter and 2 gallons of Castrol Transynd 668, which I couldn't find locally so had to get from Amazon. I was planning to pick up the internal filter & gasket kit at a local NAPA and tackle the job today. But now I'm realizing I probably need to do a more thorough flush to get the old DexVI out of there.
So my question is, what is really necessary to accomplish this and how much more Transynd do I need to purchase? I've read enough threads to realize the target has been moving on this question over the last few years. Is it good enough to just do a dump & fill, drive it a little, then dump and fill again? Or do I really need to pull the cooler return line and dump a gallon or two directly out of the system with the engine running while I put it through the gears?
I've been wrenching for 45 years and always done my own fluids but this is one of those instances where I'm pretty leery of doing more harm than good when I'm just trying to maximize the reliability of my equipment.
The prior owner was pretty good about maintenance and mostly took it in to shops so the CarFax record is pretty robust and I was able to contact the shop who did the last tranny service in 2018 only about 40,000 miles ago. Sadly it turns out they put Dexrox VI in it, which was not what I was hoping to learn.
In any event I've already bought an Allison spin on filter and 2 gallons of Castrol Transynd 668, which I couldn't find locally so had to get from Amazon. I was planning to pick up the internal filter & gasket kit at a local NAPA and tackle the job today. But now I'm realizing I probably need to do a more thorough flush to get the old DexVI out of there.
So my question is, what is really necessary to accomplish this and how much more Transynd do I need to purchase? I've read enough threads to realize the target has been moving on this question over the last few years. Is it good enough to just do a dump & fill, drive it a little, then dump and fill again? Or do I really need to pull the cooler return line and dump a gallon or two directly out of the system with the engine running while I put it through the gears?
I've been wrenching for 45 years and always done my own fluids but this is one of those instances where I'm pretty leery of doing more harm than good when I'm just trying to maximize the reliability of my equipment.
