Here we go again.
How is a lab report comparing it to Ford Honey going to help? The lab report came back showing that Red Line MTL was "more of a gear oil".
During the everlasting thread Royal Purple changed their recommended fluid for the MTX-75 from a GL4 gear oil to synthetic motor oil. Even if that is Royal Purple's recommendation, I can't bring myself to use engine oil in a trans.
I did my own research and found that when the appropriate additives are used, there is no harm (in fact, a benefit) in using GL4 or even an appropriate GL5 fluid in a trans that may not need it. The additives that elevate it into GL4 or GL5 territory don't have to be the ones that lead to break down.
I'm sorry, but I'm just not buying that Ford Honey (or the Castrol equilevant that is not available in the US) is the only fluid for this trans. I'm also reasonably sure that it may not even be the best. I will grant that it has been an excellent product in my own car, but it is not worth $20.00 a quart.
Don't forget that Ford speced Mercon ATF for this trans for SEVERAL YEARS.
