Last week I dropped by Lloyd Butfoy's shop in Anaheim, my first visit to his shop.
My ZF is with him getting a new .620 5th gear set, synchros, at least one $$bearing and .... a new $$$$$$$$ 4:22 R&P. Seems after about 80K miles on the box, a pinion gear tooth decided to start self destructing with a wear-related fatigue issue.
We spent at least an hour going over my ZF innards and I left with a much better understanding of the ZF, and an increased appreciation of Lloyd as a professional.
We also spent some time discussing ZF gear oil and I'd like to share what he told me.
He told me his website FAQ that called for GL4 and cautioned against using GL5 was in fact not written by him.
He confirmed our ZF is a spiral bevel style ring and pinion, not a hypoid style R&P.
He does NOT refill repaired transaxles upon their return to the owners. Just the lube used for assembly.
He feels Redline products are too slippery for proper ZF operation. NOTE: His opinion.
With the exception of some needle bearing cages, there are no yellow metals in our ZF. Lloyd has never seen any yellow metal damage in any ZF, something that in theory may occur with some of the additives found in GL5 products.
Other vendors have at times tooled and produced ZF parts. As Lloyd has all the original ZF design and tooling rights, he honestly believes such attempts by other vendors all fall short of what is truly needed in regards to quality.
The brass synchro rings offered by some vendors are sourced from a non-ZF application. While they appear to correctly match the genuine steel ZF synchos, in actual use they quickly fail. He cited a well-known individual who campaigns a track-dedicated Pantera who was destroying brass synchros in a matter of months. Of course racing provides increased wear and tear, but steel synchros never exhibit such accelerated wear. Lloyd feels the different heat-expansion properties of steel versus brass may account for the fast wear issue.
As for the $54,000 question - proper gear oil?
His words, more or less:
"If all the time everyone spends on discussing the proper gear oil was instead spent with an annual change of oil, GL4 or GL5, then it really wouldn't matter what type or brand of oil was used."
He also stated the proper weight is 80W90, and the use of an oil with limited-slip differential additives, or the use of an LSD supplement is not required.
Beyond those guidelines, Lloyd had no stated favorite oil. He said the controlled testing required to select the "best" oil is never going to happen, so he feels it is a personal choice. If it works for the owner's needs, that is good enough.
In summary:
Good ZF care = any quality GL4 or GL5, 80W90, changed annually
So, is this the final word on what ZF gear oil to use?
Probably not.
But it is what Lloyd said, and that's good enough for me.
Larry
Original Post
Who cares. The $2500 R&P put me in shock.
