I found this from a couple forums from back in '07. I checked Mobil's site, but couldn't find it.
From Mobil's website:
Mobil 1 MX4T 10W-40 was renamed because the product is known as Mobil 1 Racing 4T 10W-40 outside the US. Mobil 1 Racing 4T 10W-40 joins Mobil 1 Racing 2T, for two-cycle engines, and Mobil 1 V-Twin 20W-50. Be assured that no changes to the Mobil 1 MX4T 10W-40 formulation occurred during this name change. Same great product, new name.
If this is accurate, the MX-4T would have to be really old stock. I've also used the 4T for many years and love it.
Perfect, Thanks everyone for their input. Sorry I have one more dumb question.. Since we only get our oil in Liters (not quarts) should I put three liters in or will that be too much? Even though a liter is just a bit more the a quart.