It's all size and tooth dependent. Example the mtx4 diff with 50k felt like a xray diff with about 80k, spec r diff 3000 is like 5000 with cap. So the diffs being smaller I am not surprised, and he may like the feel of a spool but needed a bit more entry steering... That also could mean they found that the car works well at turnin so they went up on diff oils. I run 100-500k in my NT1 front diff, average is 150-200k. cap kit oil is 150/ 70. But keep in mind they also have 600 shock oil which is pretty thick too. It's simply a starting place .

http://www.mugenseiki.com/download/s..._ettlingen.PDF