Use a short 3/8" wobble extension, place a short 1/2 inch drive only half way on to the short wobble extension so its a little loose and can angle into the differential oil plug. Remove the plug and pump out old oil, pump in approved new Mobil 1 synthetic gear lubricant LS 75W-140, be sure the car is level when when draining and pumping in the new differential oil, once the new oil starts over flowing out while pumping, replace plug and your done, it's filled correctly. The differential took about two quarts. Takes just seconds to remove and reinstall the threaded differential oil plug using a 3/8" wobble extension.

 

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Graham