Drain plug on E320 auto tranny
 

When changing the ATF on my '96 E320, I spotted a small drain plug with socket head. Having never enjoyed the experience of removing an oil pan while it's still full of oil, I gingerly loosened and removed this plug. The oil drained out, after which I proceeded to remove the pan, change the filter, and re-install the pan with a new gasket. The little drain plug seemed flimsy to me, though, almost as if it wasn't designed for regular removal. I reassembled and inspected several times for leaks and never found any. Now, 25K miles later, I noticed a wet spot spreading from around the little plug -- as if it's seeping a bit. It's not enough to drop on the floor, but enough to make a large damp circle around the plug. I'm going to change it again soon. Should I replace the plug? Is there a replacement gasket for it? RTV it? Did I do a bad thing? Thanks,
John

Always replace the gasket on this plug. If there is no gasket, install a new one - I think it is referred to as a crush ring.

You also may want to consider draining the torque converter in order to do a more complete change.

Thanks, guys! I'll get the crush ring for that little plug when I pick up my parts. I'd also love to drain the torque converter if I knew how. Where do I find the plug for that?

It's easy to spot it if you rotate the engine slowly by hand while eyeballing the small opening in the bottom of the transmissioncase.

Thank you. I'll do that. Any idea of how much the converter holds? Just so I have enough fluid on hand!