Looks like 75w-85 is the correct fluid for the front Differential Oil. Not much different.

I've removed the reinforcement plate and zipped them on and off with an impact gun numerous times.

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e70 - purchased 6/2018
e36 - wouldn't pass smog at 190k 2016
e53 - transmission blew at 225k 2012
e30 - sold as it was a little slow for a DD and burning oil at 220k 2011