If your a basher that doesn't run on a track, heavy in the center is what I'd run. 25K+.
I've had a few 1/8 scale buggies and since I bash only (grass, pavement, skateparks), I wanted power on all 4 wheels with the diff being more of a "slipper" than a diff. I ran 50K in the center and 20K front/rear. It's one way to get a 1/8 scale buggy to do slap wheelies without a high $ engine in them! lol
I drove them very little with the oil that came in them. Just enough to realize I'd be frying front tires every weekend. Even with 50K, they would still unload if I was on really good traction and it was tempting a wheelie.
Heavier oil slows diff action regardless of where the diff is. "unloading" is what it's called when diffs spin out like your seeing.
On a track, a lighter oil setup allows for more turning power and usually you balance the rig properly to get good straight line traction too, but from what I've seen in vids, guys roll on the throttle vs jabbing at it like I do when I bash. Rolling on the throttle allows for less weight transfer to the rear which helps keep power going to the front/rear as well.