DEXRON®-VI or MOBIL 1 Synthetic / GM 4L60E

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We serviced all the local ambulances at the Ford dealer I worked at. The Econoline ambulances almost never had trans failures. The Emergency Response Vehicles (new Ford Explorers with the 5R55_ (5 speed auto) went through trannys at about 20-30k mile intervals, at least they didn't have to worry about fluid changes. Those were a nice smooth shifting transmission those 5 speeds. Seems like Ford tends to prefer a smoother shift than the GM's. Maybe its just coincidence that we do less overhauls on GM transmissions. And most of the failures I've seen are just due to worn out clutch packs. The better transmissions out there aren't going to be hurt by a little bit of extra fluid pressure causing a slightly harder shift.
 
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Anyone know how much a quart of Dex-VI is selling for, assuming it's presently available?

$2.75/qt from GMPartsDirect.com when you buy it in a 12-qt case (GM Vehicle Care Brand, not AC Delco). Once you figure in the cost of shipping, it comes out to $4.42/qt.
 
"I really loath them and curse the engineers that designed them with a passion"

Ouch.....have a nice day Gary.
grin.gif
 
What this discussion comes down to is failure modes. If a clutch pack is the prime failure mode in a transmission, then "crisper" shifts which provide less clutch heat will make that clutch last longer. However the torque disturbance will be increased with the possibility that some other mechanical element (a spline connection, thrust bearing, shaft, or whatever) will experience higher loads and fail sooner. If clutches are not the prime "weak point", then making shifts harsher may only accelerate the initial failure.
 
It all depends on how hard that shift is. Most trannies shift way too slowly. A mild increase in the so-called "harshness" will do much to extend the life of any tranny. And, most cars don't have enough power when stock to stress the components in it. There is a big difference between a non-felt seamless shift, a "crisp shift", and a "harsh shift".
Most trannies are overengineered for smoothness(timed slippage) and underengineered for longevity(inadequate sump capacity, poor lubrication channels, and pathetic OEM cooling). The aftermarket seems to have most transmissions covered with simple VB mods that improve longevity and shift crispness.

Concerning other component failure, I'd rather replace a U-joint than a tranny any day. Too bad that this is difficult in some vehicles. Maybe a simple grease fitting added to some of those "wear" components will increase its life. Oh, who am I kidding, I haven't seen grease fittings on too many new cars or even drainplugs on sumped devices. All these wannabe "lifetime" fluids are great for someone who trades their car in every couple of years.

I also didn't see any problems associated with B&M ATF. If it truly is a race transmission, it will be serviced, filtered, cooled, maintained, and built well enough not to "shred itself". Sounds like someone was use the B&M fluid as a bandaid for a poorly assembled/maintained tranny.

Bummer, $2.75 for a quart of DexronVI, I guess it isn't a full synthetic. Thats enough of a reason for me not to even want to use it. I'll stick with Redline/Mobil1/Amsoil ATFs.
 
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