Diffs, transfer case fluid warm before draining?

[spooltime]

I scanned through the DIYs and the pinned thread on fluids and may have missed the answer to my question, but I'm wondering if like for the engine oil, it's better to drain the diffs and transfer case while the fluids are warm in order to achieve more complete drainage? Or does it matter? I know, probably a dumb question but I had to ask since I'm planning to do this in the very near future.

[JFP in PA]

I scanned through the DIYs and the pinned thread on fluids and may have missed the answer to my question, but I'm wondering if like for the engine oil, it's better to drain the diffs and transfer case while the fluids are warm in order to achieve more complete drainage? Or does it matter? I know, probably a dumb question but I had to ask since I'm planning to do this in the very near future.

Warmer lubricants will always drain quicker, but I don't think there is any definitive evidence that they drain more completely, although it would intuitively seem like they should. I wouldn't be overly concerned as when the car is in a shop on a lift, no special efforts are made; the oil stops flowing out, it is done.

One word of universal caution on draining gear oils from transmissions and the like: Always remove the fill plug before removing the drain plugs. That way, you never find yourself staring at an empty gear box with no way to refill it.

[hahnmgh63]

Hot or cold I don't think it really matters but if it's cold you may let it drain a little longer. I'm anal so I always let mine drain overnight (Engine, trannies, Diffs) and for the engine at least, I fill filter with Oil before installing.

[clarksongli]

I would agree that warm fluids flow better than cold. The one difference, not sure if it matters, is that for diffs and transfer cases, the system is a bath system....no oil pump....there are some other cases (jeep has one) that there is a oil pick up and pump, but not for us.

If you are concerned about full change over.....i would drain and fill, then drive, and then drain and fill again.

On a side note, are there magnetic plugs for our diff's? with the front diff issue we have, it would be nice to keep the metal contained between fluid changes.

[JFP in PA]

I would agree that warm fluids flow better than cold. The one difference, not sure if it matters, is that for diffs and transfer cases, the system is a bath system....no oil pump....there are some other cases (jeep has one) that there is a oil pick up and pump, but not for us.

If you are concerned about full change over.....i would drain and fill, then drive, and then drain and fill again.

On a side note, are there magnetic plugs for our diff's? with the front diff issue we have, it would be nice to keep the metal contained between fluid changes.

There are no factory magnetic plugs that I am aware of, but there is a company called "Gold Plugs" (http://www.goldplug.com/) that I've used in the past who will make magnetic plugs for you if you supply an example for them to work off of. I've used many Gold Plugs "off the shelf" items, as well as their custom program, and they make very nice units.

[hahnmgh63]

Good idea about the magnetic drain plugs for the Diffs. I just bought two magnetic drain plugs for the CTTS oil (engine) pan that I'm installing tonight. See "Anal" above, I pulled the plugs and have been draining for the last two days, also installed the filter in the plastic housing and filled with fresh oil until is soaked in and filled all the way to the top before re-installing (helps on that big dry startup after the oil change).