NO Damage to auto transmission by EOC

[turbodan]

I didn't read the whole thread, but in case it hasn't been mentioned, many automatic transmissions run the oil pumps off of the input shaft, so if the engine isnt running the transmission isn't getting any lubrication. BMW's are designed this way. Doing this for any period of time with a transmission like that will leave you stranded sooner or later. Another thing to consider is the additional wear induced by shifting in and out of gear. That wont leave you stranded unless your transmission was already on its last legs, but it will cause additional wear and premature failure.

You use so little fuel when coasting anyway, especially with newer cars which cut fuel entirely during engine braking, I doubt you'll see any measurable benefits.

[99LeCouch]

Shifting in and out of gear doesn't harm much as long as the engine's running.

As far as measurable benefits, my ScanGauge shoots up ~20-30 mpg when neutral coasting with the engine on. And I coast further since the engine isn't slowing the rotation of the moving parts in the transmission. My engine RPM's during a coast with the transmission engaged are about 900-1000, vs. 650 at warm idle. Plus my old-school pushrod V6 doesn't have any sort of fuel cut, only a drop back to idle consumption.

[mush3gan]

I EOCed in my automatic tranny Corolla.. for a while on the highway and not on highway... it was bad news. i mean the parts are still turning but there's no lubrication.. in the end, i was lucky to have gotten a maintenance check anyway, and i had no transmission damage, BUT my tranny oil was so fried it wasn't even the same color. i had it replaced and haven't used EOC since. btw, i researched after, and my car cannot be flat-towed

[NiHaoMike]

On a site about DIY EVs, there was a discussion about using a cheap fuel pump as a pump to maintain transmission fluid pressures in an automatic for EV use. Maybe someone can try that idea?

[dutchboy]

EOC in neutral with a manual transmission is fine, right? Or do manual transmissions have oil pumps running off the engine too?

[Christ]

It's not fine with all transmissions, it can still be damaging, depending on which shaft is immersed in oil.

As long as the output shaft of the transmission is the one that's slinging lube all over, or if it's a pressurized oiling system, with either an electronic pump, or a output-side pump, you're fine.

If you're unlucky enough to have a tranny w/ the input shaft slinging oil, you're probably still good for awhile, since it's just gear friction you're worrying about... The viscosity of the oil will make it hang out for a good while before it actually needs to be exchanged for fresh oil to cool and lube the bearings/gear faces, but there are claims out there that it can damage your transmission if you have an input-fed oil system, in a manual transmission.

If you have a shift on the fly 4wd system, put the xfer case in neutral, not the transmission. Just about all vehicles with SOTF 4WD can be flat towed as long as you shift the xfer case into neutral. While the xfer case is in neutral, the transmission can be put in any gear there is, since no part of it is moving anymore.

This won't work on older stick-shift xfer cases, though, as they're not even close to synchronized, and won't go back out of neutral until you come to a complete stop. (Unless you're really good at gear/speed matching.)