Has anyone tried Coastal gear oil in differential?
 

I'm getting ready to change my differential fluid and have already purchased some Mobil 1 75W-90 synthetic gear oil, but I came across some other alternatives while I was shopping. Coastal Oil has regular 75W-90, regular 80W-90, and synthetic 75W-90. The regulars were $2 per quart and the synthetic was $6 per quart. That's a pretty good deal if they are really just as good. I'm not one to put faith in a product just because it says Mobil 1, or Castrol, or whatever. If it says it meets the required specifications, then I expect that it should work. But, I don't like to experiment on my car and would prefer leaving that to the more daring among us. This is why I purchased the Mobil 1 75W-90 synthetic for my differential. So, has anyone tried these Coastal oils and had success, or failure?