Is this normal for a Ruckstell differential? I know Ruckstell oil is a bit thinner than a standard differential oil, but this almost looks like the oil in the transmission. Hoping I don't have a transmission seal leak.
You may have to copy/paste the entire link to open it. If you can't open the link, let me know. It's a shared video from my cloud.
Looks a bit overfull. Not wrong thickness though. You want a thinner oil for the Ruckstell. Once it's been run and is a little dirty I wouldn't be able to look at 5w30 and tell it different from 75-140. It doesn't look bad to me, and it's not black the way that engine oil gets. Check your u-joint ball and see how well greased it is or not. Maybe pull the grease cup. If oil just runs out of there then you may have a leak from 4th main.
Ah, thanks Seth!
As far back as I can find the under drive axle (Ruckstell) is advertised to involve no additional care or expense. When not engaged there are no moving parts and when engaged just 3 planetary gears are revolving. For lubrication of the Ford differential grease was used, Western Auto Supply (1920) advertises grease for Ford differentials the associated text says " lubricates efficiently under all service conditions and during all seasons as it is not effected by extremes of hot and cold" Dykes references grease for Ford differentials. Other Ruckstell reference documents say to pack the shifting mechanism in grease before installation. Grease is available in many forms of thickness ideally a #00, 0 or #1 is best. Thick heavy grease should not be used. The grease should be creamy and non-flowing. Place some grease on a sheet of glass in the hot sun brought to a point and it should slump but not flow. Some early reference sheets mention to have the correct compound in the differential housing, a compound consists at least two parts. As far back as I can go there is no reference for oil in any form. Packing felts inside the housing to stop oil from leaking was a jobbers quick fix for a leaking rear main that filled the diff housing with engine oil and it became a standard application. There is no end of leaking housings destroying the brakes stories. With the correct non-flowing grease this would be reduced to almost nothing.
Here's the link shortened: https://goo.gl/jtVwCJ
Did you buy the car recently? Maybe someone has overfilled, maybe it leaks in from the driveshaft. Grease up the U-joint good, (fill the cavity)
Let the oil run from the rear axle fill plug until it stops with the axle level on the wheels and start driving the car - check after some time if it's a problem.
Remember to check the engine oil before every trip.