Don't use the Regular black Permatex rtv. Synthetic gear oil eats it. The Right Stuff that you see is junk also for these oils. I just had to fix a powerdivider on a Rockwell diff because of the right stuff. It turned to jelly and clogged the oil pump. Lost the bearing in the divider. Yeh. The guy used way to much. You don't want to see any hanging out anywhere when you clamp it down. This is an issue to too much is TOO much. Maybe fine on valve covers and oil pans but synthetic gear oils eat most RTV sealants. Thats why Permatex came out with sealant for this. Two reasons. To make money and to stop the confusion on which sealant to use. Not knocking anybody but I have allot of experience with this. I don't want to see you have to do it again a year from now. I don't use RTVs on many things. I can guarantee the Ultra Grey will work. I have been told that all of the "Ultras" will work for these oils but I can't say. I haven't tried the others.