DRTDEVL wrote:
afidel wrote:
Be careful with the transmission flush, if it hasn't been maintained with regular changes you can actually cause more problems with a flush and fill then you solve.
Old wive's tale that stemmed out of happenstance rather than actual causation. Those failures wre coming, whether the transmission was serviced or not.
Just do a drain and fill, changing the filter when drained. I did this to my 1997 E150 van (same setup, 5.4, auto, 9.25 sterling rear), but I put in AMSOIL synthetic. The van shifted like new after that all the way until I lost it in the divorce at 302,000 miles. I towed a LOT with it, too, mostly a 5x14 enclosed cargo trailer, but the occasional flat deck.
Chemical flushed are unnecessary 100% of the time. Snake oil.
Its my opinion the guys telling full synthetic may think different then some here.
my 4l60e trans requires synthetic blend from factory. Because there are clutches in there I followed the spec.
Experienced problems with dex VI in gms full syn are slip issues and not being able to get out of park..
Its said to be a bit too slippery.
Semi syn have different friction modifiers and thats what I use and gm specs out
But you cant believe everything you read. Im just throwing my beliefs out there.
In the engine yes full synthetic but trans.... Follow your manuals spec.
But even in the harleys i've rebuilt I have seen the rollers bearings floating with full syn and not rolling. Strange wear patterns in the cam bearings.