What causes rear diff cover to crack after oil is changed in Subaru forester
3 Answers
^ yep, generally just overtightenting the bolts or maybe if you had it done by a shop they whacked it to knock it loose or dropped it.
When I changed the diff oil on my 2008 Subaru OutBack, I didn't have to take the diff cover off.
I'm not saying it had to be done but some shops do it to "clean it out better" or someone inexperienced, he asked "what could cause it".