Hold the phone - I wasn't going to go here again, but then I thought it matters. It matters because of the $ and that they state it is a precision piece of engineering so it should matter.
First -
No beef with RealWing, you helped me clarify what fluid to use.
Second -
The sheet I received, and I imagine it was sent to everyone for many years, states 75W140 for break in, and after.
No mention of GL4 or GL5.
I see 75W140 listed as GL5 and as GL4 or GL5 based on brand and/or use. I could be wrong on that last part, just another reason why it should be expressly laid out in writing.
Third -
If you're going to give updates to your break in procedure for future units, specifically the fluid type, then you should know, not only does it not list just a GL rating, but it's the same recommendation for after break in, and it's on the same page!
Fourth -
Based on the above, you should notify all of your existing customers and get the word out, on, I don't know, social media, or possibly on your websites, or on all the Mopar forums you claim to be catering to!
Fifth -
I went back and added a fifth, that's right, so here it is - nobody I spoke to could tell me when the change was made or why. Makes me wonder if they're still sending the sheet I received, because mine looks like a photocopy of a photocopy of a photocopy, so got to use them up before we make more.
Geez Louise.
My apologies, needed to be said.
For clarity, whether you received the outdated useless sheet I did, or something else, the correct fluid to use for break in and after is:
Red Line MT90, 75W90 GL4