I'm not a mechanic and have undertaken replacement of the rear axle bearings and brake components, on my '88 Chev V-10 Suburban. During this truck project, I've found mistakes that prior mechanics have left unfixed. In removing the old noisy bearings, I noticed that they were not greased. As a newbie, I'm being careful to do everything right. The Chilton manual says to pack the new bearings with grease. The GM manual refers to the maintenace section, where there is no mention of rear axle bearings, but indicates gear oil in the differential. To grease or not to grease, that is the question. Is there a reason not to? Will the gear oil and grease contaminate each other, or what? This seems like a small issue, but important to me. Thanks.