Gearboxes, gear oil, and levels

[veteran]

alex,

The spare parts site 'nemiga' unfortunately isn't much help. First, nemiga lists four groups of 5-spd manual gearboxes for the 2013-on Polos and I've no idea which one of them is mine. And second, only in one of the drawings is any sort of plug shown.

As for the official VW gear oil itself, it could possibly be VW no. G 052 527 A2, which I understand to be 1 litre of 'high-performance transmission fluid', nemiga giving its cost as around 45 dollars. That's about three times the cost of any other 'high performance' gear oil on the market. I'd need somewhere between 2 and 3 litres. Sure, if it really does perform incredibly better than any other of the well-known brands, I'd be prepared to spend the dosh, but otherwise ........

I wouldn't rely on just using a general car spares website and plugging in my reg. no., because when I've done that (usually, for security reasons I enter the full details of the vehicle rather than the reg. no.instead) for things like spark plugs and oil filter, they've quoted completely wrong part nos.

[alexperkins]

What’s your reg number or chassis number? PM it to me

I use VWs official parts system. Nothing dodgy.

[RUM4MO]

veteran:- I don't think that is exactly what alex is saying.
Oils like anything else will have a reasonable "width" and "depth" as regards what is in the additive package that is built into any single grade of specific purpose, in this case transmission, oil. Any company "building" an oil to meet a specific manufacturer's specification will, if they want to label up the product as equivalent to VW spec XYZ, will need to pay to get their product tested for being suitable to use that description. Some smaller oil suppliers will just use "weaker" words which normally mean that they built that oil up to meet the relevant VW spec.

One crude example, though in this case, and engine oil:- Fuchs make oils for VW Group for use in their factories and as such make it clear which relevant VW spec they meet, Fuchs also make oils to sell into the aftermarket, again making it clear which VW spec they meet, Fuchs make oils for other aftermarket oil suppliers and make it clear which VW spec they meet. When I accidentally asked Fuchs UK if Fuchs 5W-30 xyz was the same as Company Z (who they make oils for) 5W-30 efg, the answer was, "no", all oils are built to a specific spec and cost etc. So no change as you would expect between this product and any other product built in the same factory for several "firms" .

Edit:- as pointed out by "veteran" my last sentence is completely wrong, so instead of changing it and pretending nothing wrong was written, I'll write the correct version down here:- "So no exact similarity as you would expect between this product and any other product built in the same factory for several "firms" - each oil will have its own version of additives package to suit its own place in the marketplace mainly based on price"

My big blunder when asking Fuchs UK questions was due to the fact that I had heard that Unipart, at that time, were an outlet in UK for Fuchs oils, what I did not know or think about was that Fuchs supplied Fuchs branded oils to Unipart, but also supplied Unipart branded oils to Unipart, my error!

[veteran]

RUM4MO,

Maybe it's my advanced years and/or my senility setting in but I had to read that response of yours several times before it started to make any sense (as a number of connected ideas). But in the end I think I've acquired the gist of it.

If what you've encountered is truly the case, then my former and admittedly sweeping assumption about gear oils - particularly aftermarket ones - has been completely wrong. That being so, I hold my hands up and admit that, as ever in this game, there's always something new to learn.

PS. One sentence I just couldn't make much sense of at all was that last one: " So no change ..... for several 'firms'." Before that, you seemed to be saying that Fuchs had told you that all oils of a nominal viscosity/temperature performance were individually tailored to the requirements of particular car producers. But that last sentence of yours then appears to say the opposite of that!

[RUM4MO]

veteran, I think that your last sentence about my last sentence must be correct! If I can work out why I wrote that that way, or what exactly I meant to write I will post back about it

I also seem to be getting old, free bus travel is possible for me!

[RUM4MO]

veteran, I have now edited my posting that you were referring to, while leaving the original wrong sentence in - otherwise your posting would not make any sense! (that would have lead to cries of "what is he on about!").

[alexperkins]

You hit it on the nail Rum. Just because it meets a specification doesnt make it the same. Meeting is one thing, exceeding is another, and this is why genuine VW gearbox oil is the recommended choice in this instance.

Its a bit like the haldex 4WD clutch oil. If you dont use the official Haldex branded/VW supplied oil you can end up with all sorts of problems with the gear system

All oils are not equal

[veteran]

Alex, RUM4MO , iichel, et al,

I came across an old Lyndsay-Porter Golf/Polo/Jetta workshop manual of mine yesterday. The vehicle models in it range from the mid 1970s to 2001. While perusing the diagrams and text in its section on Transmission I noticed that, in some cases, there was a small filler plug adjacent to the righthand gearbox output shaft where it couples to the RH driveshaft. This is the same small plug that I've mentioned as being found on my Match Edition Polo, and its size and position looks very much like those in your posted engineering drawing, iichel. The text accompanying the Porter diagram describes this as the 'Final Drive filler plug'. The inference is that the output shaft runs in a separate oil supply of its own. So I think my hunch, alluded to earlier, might possibly be correct, and that the main filler plug for the gearbox is a bigger one that's situated instead on the lefthand side of the gearbox, near to its rear.

Whether or not the Final Drive needs to use the self same gear oil as the rest of the gearbox is unknown; the Porter manual gives no further detail. And one has to assume that the requisite amount of oil for it is, as with the main body of the gearbox, as when it sits level with its plug.

If I'm correct about that, this could mean that emptying and refilling the gearbox might not just be a matter of dealing with that larger filler plug. You might also need to empty (if need be) and refill - or at least check the level in - the Final Drive cavity.

[alexperkins]

On the TT albeit it’s quattro, it has two drain plugs as one is for the transfer box. They are fed from the same oil supply but both have to be drained to be changed. You fill the box to max, Then you run the engine in gear for 5 minutes. You then check the level and top up as oil has moved over to the transfer box

I haven’t yet seen a non 4WD gearbox that has a two step drain process. I’ll check the Elsa manual for your polo and see what it says, though I’m quietly confident it’s single drain single fill

[veteran]

Been looking at the Transmission sections in the very comprehensive workshop manual for my old Golf, and in there it says "On cars with manual transmission, the differential shares the same gear oil as the transmission."

Of course, what was the case two decades ago and for a different VW vehicle may well no longer be relevant for 2014 - 2017 Polos. But this could be an explanation for the drawing and instructions that you found, iichel. So, in the case of the current Polos, it might indeed transpire that the diff/output shaft shares the gear oil with the transmission, and therefore that small filler plug adjacent to the output shaft on the righthand side might actually be the true filler plug for the gearbox. But then if that's so, what's the purpose of the bigger plug? I'm not absolutely sure about this because I'm relying on what I saw several weeks ago when under the car, but I think the latter lies a bit lower on the gearbox casing, which would mean that if you undid it without first draining the entire box quite a lot of oil would pour out.

It strikes me that, for our particular Polos, understanding this is pretty critical and needs to be confirmed, one way or the other. If instead you were to glibly assume that the plug on the LHS was the filler, and that level isn't the same as at the diff/output shaft, then following a refill you could unknowingly be starving the latter of oil.

[RUM4MO]

Just to throw into this mix of maybe facts, the parts listing for the manual boxes for both power outputs of this engine show that there are two "plugs" and both have the same part number. How curious, oh, and no drain plug shown, unless one of the listed plugs is the fill/level plug and the other is the drain plug - though the parts listing kind of infers that these plugs are roughly opposite each other, the correct facts will be out there somewhere, it will just take time to find them!

[alexperkins]

One filler one drain. Just checked ELSA

Correct filling procedure:

When filling with oil, note the following:

–
Remove oil plug -arrow-.

–
Fill with gear oil to lower edge of filler hole.

–
Screw in plug -arrow-.

–
Start engine, engage gear and allow gearbox to turn for approx. 2 minutes.

–
Stop engine and remove plug -arrow-.

–
Top up with gear oil to lower edge of filler hole.

–
Tighten bolt -arrow- to specified torque → Fig..

[veteran]

In practise, though, there are TWO filler plugs on the gearbox. Or at least there are on mine. So, it's still an open question as to which of the two should be used. Looking through all my VW manuals, what I've found is that, on petrol vehicles, the filler plug is up by the diff/output shaft but, on diesel vehicles, the plug is located further down on the LHS of the gearbox. However, this does also seem to depend on the engine capacity as well. Why this should depend on petrol v diesel I've no idea, but what might have happened more recently is VW doing some consolidation and cost-cutting, by fitting the two different plugs on the same gearbox. This is only a theory of mine, though. Other than that, I can't see why the second plug should be there.

When you looked at ELSA, were you able to see a diagram or drawing of the gearbox, showing details of the LHS of the gearbox (to be able to see the second plug)? The drain plug will of course be on or very near the underside. In trying to pursue this myself, I found that the diagrams/drawings of the gearbox available at erwin, ifinterface.com and nemiga simply didn't show the LHS in enough detail. Consequently, it'd be so easy to conclude that there was just the one filler plug.

[alexperkins]

I’ve spoken to my mate who is a dealership master tech today and there’s definitely only one fill on these. The other is a blanking port used in manufacture and not maintenance

I have a diagram which I’ll post when I’m back in front of my Mac tomorrow

[alexperkins]

Here you go