Interestingly, and I have no idea why, but halfway through 2013 the VAG 02Q gear oil changed.
It went from G-052-171-A2 which is a 70w75 to the G-052-527-A2 which is a 75w80. So bucking a trend, they actually went
thicker which leads me to believe maybe they learned something? The newer stuff is also listed as "high performance gear oil" in ETKA, the older stuff is not.
I tend to want to use the thicker stuff, unless I lived in an area that was cold much of the time and had EXTREME cold temps in winter, although with modern synthetics that is less of a problem.
Funny anecdote about VAG spec gear oils: years ago I swapped the 5 speed gearbox in my '87 Mazda B2000 when it lost 5th gear rather suddenly at 346k miles. I sourced a used transmission, which only had 180k on it, from a wrecked truck. The used transmission came drained, and I was going to put fresh stuff in anyway. I just put in some generic gear oil, Mazda had no specific type just an 80w90 GL4/5 gear lube. Got the truck back together, it shifted fine, a little tighter but I expected such as the unit had much less use on it.
That tightness seemed worse that winter, however, so I decided to try something fancier. I put the same G-060-.... gear oil in it I had been using in my FWD transverse Volkswagens (the RWD Mazda, like them, had no hypoid gears to worry about) and was AMAZED at just how much better it shifted. Night and day.
So one day, a coworker was messing with his 1995 Bronco, getting it ready for winter (it was his backup vehicle, not a daily) and lamenting it being like driving a drunk dinosaur in comparison to his Geo Prizm, and especially due to the much less precise manual gearbox (yes, Ford sold a few big Broncos with the proper number of pedals). I asked him what fluid it had in it (Ford, oddly enough even though this too was a Mazda transmission, spec'd ATF in them !!!! ). He said whatever it came with. So I talked him into changing it to the VAG stuff I had (I think it was a Motul branded product, maybe Liquimoly).
He was instantly shocked at how much better it shifted. And this was an actual gear oil, a synthetic one, so should have been thicker than the ATF, yet still allowed not only easier shifting but made the slight [normal] gear whine it had go away almost completely.
Fast forward a few years, another coworker, who had a 1987 BMW 325e, wanted to change the gearbox oil (Getrag 5sp), and could no longer read the tag on the side as to which fluid it used (BMW could have used one of three different types). So he too opted to put some VAG spec stuff in at my recommendation. While he had no specific problems or complaints prior, he was just doing this for PM (he had recently purchased the car), he said the next day he was shocked how much better the transmission behaved. I still work with him, he still has the 3-series, and that lube is STILL in there!
So, as soon as I got my current '96 F150, guess what fluid I put in its Mazda manual gearbox? And guess what happened?
I am not picking any specific brand here, just noting that I think VAG's feeling on gear oil is possibly pretty good, regardless of whose box it is, and that it may be wise to stick with it.
I have since swapped the fluid in my dad's '99 Ranger, too. With similar improved results. Why on Earth Ford called for ATF in a manual gearbox being used in a TRUCK I have no idea, especially when Mazda themselves never did, and that is who supplied the M5OD units for all the F150s, Rangers, Broncos, Bronco IIs, Aerostars, and even a handful of E150 vans. May be why Ford gave these trucks such a pathetic tow rating, too. (I have exceeded that many, MANY times, LOL...).
