Was underneath changing transmission fluid and noticed this leak, which looks to be where the engine is bolted to the transmission? Has anyone seen this and know how to address?

IMHO you need to clean the area up then check it after a day or two to see exactly where it is comming from, if it is from the join then it's either the engine crank seal, or possibly the gearbox or torque converter, whichever it is the box will have to come out to fix it...  Pete
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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

My 2012 WM had that. Leak bad enough for drips to appear on the ground. LR said it needed a new gearbox, fitted under warranty. I hope yours isn't as bad. Only Range Rovers since 1988

Well there's hope that it might not be a crankshaft seal and it might be an oil leak that is slowly finding its way down. Christian from LR Time dropped his tranny and found out at 21:30 in this video that he actually didn't have a crankshaft seal leak and that it was residual oil from another leak that made its way down through the mating surfaces. I have the exact same symptoms. No visible engine oil anywhere on the sides, just that one spot. I think it's time to invest in an inspection camera. But in the meantime I'll see if I can see anything from the top once I am done with the full driveline fluid service. 2023 L460 Range Rover SE P400
2019 L405 Range Rover ATB LWB

If you pop that round circular rubber bung out of the bottom of the bell housing you'll be able to wipe your finger around the inside of the bell housing at the bottom. If it's dry in there then it's not your crankshaft oil seal, if it's wet in there then it's either the crankshaft oil seal or the seal in the front of the gearbox.

Both of those would be fairly labour intensive jobs to resolve unfortunately.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior
2013 Range Rover Sport SDV6 HSE Black Edition in Santorini Black with Ebony Interior

Pulled off the bung and there is in fact a very very thin amount of oil. You can’t even see it on your finger when you wipe it, you can just feel it.

Do you happen to know what that rubber bung is called? I need to get another one cause I tore the dried one. Not a must do now to drive thing but I’ll get one on Monday.

Is this something I need to address immediately? Doesn’t seem like a big deal, it’s so minor.

What symptoms does this cause other than a minor slow leak of oil?

I also have this weird vibration at 1000 Rpm’s I can’t put my finger on. Only when I run at exactly 1000 RPMs can you feel it. And when it passes through 1000 RPMs. It feels like driving on grooved asphalt if that makes sense. 2023 L460 Range Rover SE P400
2019 L405 Range Rover ATB LWB

Mine was the rear main seal. My extended warranty covered it. Cost was around $1,500 Canadian. Dan. 🇨🇦 2013 L405 5.0 SCV8

I have a similar leak detailed in this thread.

https://www.fullfatrr.com/forum/topic73096.html

I'm not 100% convinced it's not from the top yet especially seeing Christian's video.
When I get time I'll strip the top down and remove the EGR and replace the gasket.
Mine looks dry at the top end but even with a camera you can't see much in the V behind the EGR.
If you find the cause please let us know. 2012 TDV8 4.4 Westminster Santorini black
2016 Discovery 4 Landmark
2002 Defender TD5

Yeah, my leak, wherever it is, is just starting or is super super minor. The metal underbody covers show no oil on them or very little. And I cannot visually see any oil anywhere except for where I circled in the pic. I guess I will monitor. My 2019 has 99k miles on it right now. I’m sure it will get worse and be more evident at some point. How many miles is on yours?

Also I don’t have turbos, I have a supercharger so definitely not turbo lines. 2023 L460 Range Rover SE P400
2019 L405 Range Rover ATB LWB