TomB275

Using the wrong type trans fluid will often cause a failure of the clutch facings depending on the level of wear on the unit.

koakako

That's true. It does have to be compatible to the vehicle in question.

On that note, the best write-up I've seen regarding the 'old fluid myth' is in Steve83's posting of of the Ford TSB regarding "Drivetrain Lubricants". The chart and instructions themselves are valuable information, but the write-up in question is titled "THE DANGER OF CHANGING THE ATF", found below the chart. This repeats what I was saying above, though with more clarity and better wording...

TSB URL --> http://www.supermotors.net/registry/media/491904_1

ohYew812

Questionable at least when this is how it is preceded...

"THE DANGER OF CHANGING THE ATF

I'm no slushbox expert, but this is how I understand it:"

ibd2328

iTrader: (2)

I can promise, no harm will come when changing ATF

jollyroger331

Hope your right IBD, just changed mine two weeks ago then drove her up north for vaca. Home for a week and a half and heading out Sunday pulling this beast on our annual camping trip, about 450 miles round trip.

ibd2328

iTrader: (2)

You should be good. Most problems come when people fail to replace filters and make sure gaskets are sealed

jollyroger331

HA ! Funny part is, when I got done putting it back together, I walked in the garage and there sat my new filter. Thankfully I decided to install a drain plug so it only took about 15 minutes to drain it drop the pan install the filter and replace pan. Damn senior moments.

ohYew812

HOLY CRAP!! A stock F150 can pull that??

jollyroger331

I'm not completely stock. I have a large trans cooler, an SCT programmer, a 2" add a leaf and an e-fan but yes it pulls pretty well. Last year I took it 550 miles up north and back and she did just fine. Not bad for an old truck with 167,000 miles.

koakako

Well, if the oil wasn't that bad then I'm sure you'd be fine. Like Steve had written under that TSB, the danger is if the new oil "cleans" out all of the old debris within the trans and clogs up the new filter. Something that I did on my F-150, but that was okay because I was expecting it.

I bought the truck ('85) for $900, because it was in such terrible condition, and easily over 200,000. Over the years I've easily spent about $1500 on parts, and probably a solid month of time making things right. (Over the space of several years, of course.) I wasn't a bit surprised to see the trans fluid looked like week-old coffee and smelled like the bottom of a backyard grill.

I'd be worried, if the oil was old and brown, to take the vehicle for 500 miles or so right after changing it... but if you've kept up maintenance and the oil wasn't TOO bad, then it's probably not an issue at all. That decision, obviously, is up to you.