Hey guys,

Sorry for this, but it's not directly third gen related though perhaps good for anyone with an auto transmission.

Friend of mine at work had me go and look over a 98 Jeep Grand Cherokee before he buys it and while it's got the wear and tear I"d expect on a 98, I didn't think it would have been a bad purchase for $1000.

One thing I do have a question about and that's the transmission fluid. It looks really red-brown and burnt and not nice and pink-ish. It doesn't "smell" burnt though (I have smelled burnt tranny fluid so I know that smell well...on my mom's Dodge). On my advice after he decided he wanted it and bought it he took it in to have the fluid changed but was told by the shop that this may cause the transmission to fail. Apparently transmissions like old fluid? One upside I guess was that there was no metal shavings in the fluid and having ridden to work in it for the past week, I can say it seems to shift "ok" though a bit hard at times as it bangs through the gears. Would it be a good idea to change the fluid and filter or just let it ride till it dies or he leaves England in 3 years?

 

I've never bought the idea that 13 year old transmission fluid should be left in the vehicle. Especially when it's not the stock colour any more. I'd get it flushed out and new filter and new fluid put in.

 

That's kind of what I was thinking but I've also read alot of posts where people seem to think it's sometimes better to leave the old stuff in as it's the "Glue that holds it together" where the new fluid can cause it to start slipping etc.

 

I'll go the opposite - let it ride.

After years of not being changed - the tranny slipping (which all auto trannies do always) releases particulates into the fluid that act as a friction additive that helps the clutches and such continue to "stick" to one another. Replacing old fluid like that often times results in a tranny that slips when it didn't before - since those particulates are no longer present. Tranny fluid should be changed every 60,000 miles - if they go above 100,000 with no change, then they should remain untouched or else you risk it slipping.

I've seen it happen before - perfectly fine tranny slips after fluid change - but I'm sure there will be debate on the merit of the arguement. For me, it's not a risk I would take - if it ain't broke, don't fix it.

 

Trans fluid is only red because it is dyed. This is a temporary dye that eventually fades and the fluid then looks like light brown motor oil. I think changing the filter and the 3 quarts it loses would be the right thing to do. I would not get it flushed for the reasons stated above.

 

If the transmission still is in good working order, then do a complete fluid and filter change. I have been doing this for about 35 years now, and this does not ring true with the fluids of the last 25+ years. I have not seen "sludge" in anything in this time period when tearing down units. Many years ago we did see some that had sludge in them and when we changed fluid, "sometimes" they would start to have problems, but this was back in the late 1970's and early to mid 1980's. The fluids over the years since then, have improved very much in terms of them not producing any sludge in them. Do the complete fluid & filter change yourself if you can. I do not trust the people and how they flush these units out. Too many crooks out there who want your business, and this is one way they can get a transmission job out of you.

 

I know I can change the filter by dropping the pan and some of the fluid also this way. Without a power flush machine (We used one when I worked at Sears to do a fluid exchange), how do we do a complete fluid exchange?