Originally Posted By: neilLB7
Nonetheless...I've actually read some pretty good arguments for using 5W-20 or 5W-30 synthetic motor oil in transfer cases by one particular rebuilder of GM HD pickup transfer cases that were prone to certain kinds of failure. In fact...it's the only way their warranty will be valid after a rebuild. I owned a 2002 Chevy HD2500 4x4 Duramax for several years and switched to Mobil-1 5W-20 in the transfer case with no observed problems over a few year period.
I'm going to take exception to that portion of your statements. I realize your specific topic is about the Ford fluid, but you brought up a topic I'm very familiar with, and want to address. Especially concerning the possibility of folks mis-understanding the fluid choices ...
I did a VERY detailed write-up over at DieselPlace several years ago about the topic of motor oil in the t-case in GM trucks. I would ask anyone to go over there and read it (maintenance and fluids section, as I recall).
The source of that motor-oil topic:
here is the direct link to the RSG article (read what is page 49 on paper):
http://www.rsgear.com/articles/2007_03.pdf
Essentially, Mike Weinberg of RSG noted that when they did reman jobs on those NV261/263 cases, they were often low or empty of fluid. He simply guessed that motor oil would last longer in the t-case than the GM spec'd ATF (formerly DEXIII). That's it; nothing more than a shade-tree swag because in his mind "thicker is better". I know; I actually interviwed him directly via email about the topic. He wrote an article for an industry trade magazine; that is where the topic originates from. He did absolutely no research whatsoever into the issue of fluid compatibilies, fluid properties, etc; it was a swag for him based upon shade-tree-mechanic mentality. Also, I'll note that he never said to use "synthetic" oil, just "5w-30 motor oil".
I also did thorough research by talking with NVG (New Venture Gear who mades those t-cases at the time), and the Reman Industry association, and Jasper Engines (another reputable reman entity), and a host of other sources. I checked directly with Amsoil; I looked up many other lube sites, etc. I may be annoying, but I'm nothing if not fair and detailed. I could not find one single source aside from Mike that makes that recommendation. Every single other source specfically states to follow OEM specifications (in this case, use ATF).
In short, Weignberg blamed the lack of fluid in the t-case on the ATF. His opinion is that it evaporates and motor oil would not. Really - that's his simple explanation? Last time I checked,
fluid levels are the responsibility of the operator. If one is so stupid as to run your t-case completely empty, no amount of ATF, or motor oil, or gear oil, or banana-cream pie filling, is going to save the equipment. The complete lack of fluid resulting in the destruction of equipment is not the fault of the fluid; it's the fault of the operator! A failure to maintain adequate fluid level is not akin to fault of a lube.
Further, he also not only said to use motor oil, but to over-fill it by one quart. Since it is a two-quart system, that is a 50% over-fill! For those who have worked around gearboxes, it is often a VERY bad idea to over-fill, as aeration can be promoted. 50% over-fill is not needed. And I have to question his logic here ...
If he believes that motor oil would not evaporate, then why the need to over-fill?
If he believes that over-filling is a necessity, then is that not an acknowledgement that fluid levels will indeed fluctuate, and that the owner EVENTUALLY is responsible for maintaining the fluid level, REGARDLESS of what brand/grade/base-stock is in the equipment?
And here is a grand sense of silliness I see in his article; he specifically states that after installing his brand of remanufactured t-case, the owner should check the fluid "
every 5,000 miles and change every 10,000 miles". Really? So, he recommends that we should check our fluid levels, but he blames the ATF for a condition of being low rather than a result of poor maintenance habits? Would not that very same condition happen if one never checked the motor oil in the t-case he recommends? If motor oil is the end-all/be-all solution to this problem, then why does he recommend to check it every 5k miles? I actually own one of these NV261 units; I can assure you that even ATF lasts WELL past 5k miles!
Now, in theory, if evaporation is your concern with ATF, then are there alternatives to motor oil? YES! I would even go so far as to say that there is an excellent choice that stays 100% within the confines of OEM specs, and yet upgrades the fluid. Yes, folks, I'm actually going to recommend the use of synthetics here! Why not use a DEX/Merc type fluid that is synthetic based? Why not use an ATF such as Amsoil "ATF" or "ATD", or Mobil 1 ATF, or any host of other synthetic ATF products that are already targeted directly at the former Dex/Merc applications? What silliness is it that one thinks a synthetic motor oil would save the day, but a synthetic ATF would fail?????? Pure lunacy!
Now - none of my discussion says that motor oil will not work. Some folks use it with no problems whatsoever. The evidence is, at best, anecdotal. I've seen no evidence that motor oil has failed to protect these t-cases. But then again, I've not seen any evidence (excluding pure fluid neglect) that ATF does not also protect very well.
When you really pick, scratch and dig into Mike's suggestion, it's full of iorny and contradictions, and is a simple swag and nothing more!
There is even a bit of irony in the world, in a larger part. I'll explain ...
In the world of Harley-Davidson motorcycles, they use a chain-driven primary case. The approved H-D fluid for that application is, essentially, motor oil (a rose by any other name ...)
And yet, there are some H-D faithful that will always be seeking something "better" (sounds like some BITOGers we know, right?). And so, in their vain effort to find this "better" alternative, they eschew their H-D approved oil in favor of ... wait for it .... ATF! Gee - seems odd to me. Some GM owners would walk away from their ATF in favor of motor oil in their chain-driven t-case, but some H-D folks will walk away from their motor oil in favor of ATF in their chain-driven primary gearbox. I've seen both the t-cases and the primary cases apart; they are NOT much different in design and context, folks. And yet the grass is always greener on the other side of the fence, is it not? Talk about irony!
The "approved" fluid in those GM t-cases is ATF (former DEX III). That is what GM spec'd; that is what NV designed for and field tested.
Will motor oil work in this type of application? Apparently it will. And perhaps that's an indication that the applications themselves are probably not really very sensitive to fluid selection. But warranty is very senstive.
Let me summarize with this: I don't care what other folks use; do as you wish. But I get miffed when folks state that motor oil is a proven solution to this problem. It's not; it's a swag from a guy that did no research and has serious flaws in his logic on this topic. I'm cannot say that a motor oil would assure failure, but I can state with 100% certainty that keeping the properly spec'd fluid at the correct level would mean you'd never have to buy one of Mike's remanufactured t-cases in the first place!
Caveot Emptor!
Rant over.
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