you overfill the getrag with 5 quarts of synthetic correct? after draining it of course. I am going to do this over the weekend and want to know. I hear synthetic is too thin and will make the seals leak but i wanted to hear ur opinion first.

 

I've been running mine overfilled with synthetic for the past 10k miles. No leaks yet.

 

Weather or not an oil is synthetic or conventional has nothing to do with it's viscosity. 5-30 is 5-30. Synthetic simply stands up to higher heat and shearing forces longer than conventional. I've been running Valvoline 5-30 conventional in my tranny and have been swapping it every 15-20k with no issues. I would consider extending the interval slightly if I were using synthetic.