Hi, General question for community. What are your thoughts regarding whether or not to change the Transmission fluid on a high mileage Discovery (series 1 or 2) with unknown history!
My concern, as I'm sure many will be sympathetic to, is actually causing a problem in the transmission by changing the fluid rather than just leaving it be. I have a heavily modified D1 that I've off roaded pretty hard for the last 10 yrs, where I've taken this vehicle from about 110k miles to 130k miles - for this vehicle I decided to just leave the transmission alone and have had no issues! I've just recently purchased a D2 with 104k miles and am now considering the same dilemma! Should I service the Trans or leave it be!
Any shared experience would be greatly appreciated, especially if anyone has actually changed the fluid of high mileage, unknown history vehicles and not had any issues.
Thxs, Ian

 

I just changed my fluid and filter 5k miles ago at 120,000. I was hitting all the bolts with penetrating fluid for about a week following up to when I did the job. One of the smoothest jobs I’ve ever done on this truck. Follow Atlantic British video tutorial. I didn’t have any shifting issues before but afterwards the shifting was so clean and smooth. Now I’m ready for another 60k

 

Any tips on the type of ATF to use in our trucks?

 

Valvoline Dex/Merc, you can buy it by the gallon from walmart for under $14

 

I did the trans fluid change at about 110k miles. No history of ever changing it (exhaustive paperwork from POs). Got the kit from AB, Valvoline Max Life Full Synthetic, a big bottle of Lucas Trans Fix. Started to treat the bolts with penetrating oil one week before. The whole process was very easy (watch the AB video). Before draining get the fill plug out (so you are not stuck with an empty transmission in case it is seized). For topping up I used an electric suction pump (ebay $18). So far 15k miles or two years driven, no issues.

 

I have an 04 with 112k miles that shifted great, and haven't changed it yet.
But, I do have the fluid and filter,
And, I also bought a D1 transmission pan that has a Dipstick for when I do.
That will make things a little easier in future, including pouring fluid into a funnel, vs pumping it in.

 

Do a drain, filter, and fill.

 

Did you guys replace the pan clamps as well? They're included in the AB kit & video but tough to imagine how the existing ones on the truck would be a wearable item...

 

I didn't replace the clamps, because they looked good and weren't corroded. They don't wear, but corrosion can seize the bolts.

 

Hmm. I'll poke my head under and look at hte bolts. If I'm lucky, they're spewed with enough oil that they haven't had a chance to fuse together with rust.