Gearboxes, gear oil, and levels

[veteran]

Yes, I've already seen that, as it happens. But it's not answering the mystery.

Believe me, there IS a second filler plug. I DIDN'T imagine it. It's on the LHS of the gearbox. In fact, in my case, there's some signs of oil seeping out from around it and dribbling down the casing. It's hex-keyed; I'd say either 14mm or 17mm. The drain plug, on the other hand, is a smaller outlet and is situated on the underside of the gearbox, more-or-less where you'd expect a drain plug to be.

If you've been paying attention you'll have read earlier that RUM4MO has also spotted two filler plugs on the gearbox of his wife's recent Polo.

If it weren't for me having a lot of backpain at the moment, I'd put my Polo up on my ramps, get underneath, remove the undertray, and take some photos of these various plugs, to post here and demonstrate what I'm on about.

The bigger plug on the LHS isn't any sort of 'registration plug', no matter what your VW workshop contact maintains. Instead, in position, type and size, it resembles the filler plug found on some slightly earlier Polos and Golfs. I've photos in various workshop manuals that show it quite clearly. VW would surely not put a 'registration plug', or any other sort of manufacturing plug, anywhere where it could be mistaken for a filler plug, or vice versa, as the consequences of getting them mixed up could be disasterous?

[alexperkins]

VWs argument on this is the service manual must be strictly followed with reference to the imaging to ensure the correct hole is used for filling.

Can you upload photos of said maintenance photos? Curious to see it.

Im not saying you imagined it. My point was its not there to be used

[alexperkins]

Ok, Ive double checked your VIN against ETKA

You have a PED gearbox



Number 4 is the sealing plug, there is no drain plug listed, which implies the drain and the fill are both located on the sides rather than one in the base

[veteran]

Woh! Steady on. Hold the horses for a moment.

I gave the gearbox type as 'MG5'. That's how it's described in the tabulated specs at the back my Driver's Manual. Presumably, it simply means 'manual gearbox, 5-speed'?

The gearbox code will be something quite different, I think. The code might be on a paper label somewhere on the gearbox (can't recall seeing a paper label, though), but more likely will be be stamped into a flat on the gearbox casing somewhere. Very little of the gearbox can be seen from 'up top', so a search for that code and anything else I've in mind to do concerning the gearbox will I'm afraid have to wait until the Spring, the time when I plan to get underneath the vehicle again to check a few things out and to apply some waxoyl to the subframes, coilsprings and dampers.

[alexperkins]

Correct, MG5 is just manual gearbox 5 speed

I edited my above post - you have a PED gearbox (verified on ETKA)

There are only two sealing plugs on this gearbox, both are located on the sides rather than the base

The fill plug can be seen here, which is on the drivers (UK) driveshaft side



The drain plug can be seen here, which is on the passenger (UK) driveshaft side

[alexperkins]

From ELSA

Differential housing - drain is 3



Clutch Housing - filler is 14

[veteran]

Alex,

Thanks very much for providing that ETKA exploded diagram. It's the best of its kind I've seen so far.

Yes, that looks vaguely familiar. And, as you can see, there are TWO plugs present. On my gearbox, there's a drain plug on the underside. A bit odd that it's not shown in the diagram. When last under the car and looking around the gearbox I didn't take any special note of the gearbox drain plug, save that there was one (or what appeared to be one). My understanding is that, for some years now, VW has made that drain plug a splined, tamper-resistant one, requiring a splined socket-bit with a hollowed-out centre. Clearly, VW tries to put off all but the very determined from draining out any of the gearbox oil. So, possibly that's a reason why they don't even show it on this diagram?

If VW doesn't provide a drain plug of any kind on a gearbox, then the only way you'd ever remove every last drop of the gearbox oil would be to remove the entire gearbox from the vehicle. Then once the gearbox were out, you'd have to turn it on to its side, remove the LH plug, and then empty out the oil from that hole. Most of the oil could perhaps be removed by using a syphon pump, inserted through the LH hole, with the gearbox left in situ.

As an aside, the Polo belonging to RUM4MO's wife is the same model as mine, I gather, and is only about a couple of years older. RUM4MO indicated to me that shortly he'd be doing some maintenance work on that Polo and that he'd take the opportunity to check out some of the things concerning the gearbox that I've mentioned. RUM4MO?

[veteran]

Ah, in between my last posting you've added some photos and more exploded diagrams.

Although those begin to give my contention more credence, I'm still not 100% convinced that what you've highlighted in green in the second photo is a drain plug. If, looking at that photo, you mentally correct the sitting position of the gearbox when on the car, that plug - which you've presumed to be the drain plug - will end up about half to two-thirds the way up from the bottom of that part of the gearbox. Therefore, you'd only be able to drain out about half the oil. Again, mentally compare its position to the the plug that's adjacent to the output flange. Level-wise, they're not an awful lot different.

Afterthought: Could it be that there's ONE filler plug but TWO drain plugs? Could it be that the differential housing and the other part of the gearbox use the same oil but that they are compartmentalised, thereby requiring TWO drain holes - one on the LHS of the diff housing, and a second, smaller one on the underside of the gearbox?

[veteran]

What does 'PED' stand for?

[alexperkins]

The oil compartment is actually quite shallow so even though it doesn’t look much (it’s about 2 inches lower) the drain plug is sufficiently low enough to empty the gearbox sufficiently

PED is the code VW assigned to your gearbox. Means nothing apart from an identifier

I haven’t presumed anything. I’ve literally annotated based on the ELSA diagrams and procedures.

[RUM4MO]

I changed the wheels/tyres on Wednesday but was too cold/lazy to take the under cover off again - so sorry for that!

I think that I said earlier which side that I had spotted the plug with the large hex recess, and I think that what I saw tied in with what iichel posted earlier and alex posted today - ie the fill/level plug is on the RHS of the car.

I don't remember seeing the same plug on the other side so would need to look at that side a bit more - maybe I could see that without taking the under cover off, that side of the car is near the wall in the garage. Also, I don't remember seeing a drain plug on the base of the assembly - and that ties in with the parts cat diagrams that I've looked at.

The gearbox on my wife's Polo is a 6MT or in VW speak a MG6 type PRQ, so is very similar to the MG5 externally.

[veteran]

It looks as though this matter's unlikely to be resolved unless/until I access the actual gearbox on my car and take some pictures for you to mull over.

Incidentally, I've written to three relevant gear oil suppliers for their comments on whether their products are equivalent to VW's G 052 527 (A2). I've not heard from any of them yet. However, it's early days.

[alexperkins]

I’ll check the Elsa exploded view on the PRQ. The 6 speed has a fairly different housing to the 5 speed

[RUM4MO]

I thought that both the later 5 speed and the later 6 speed are from the same family of gearboxes - judging what I found using the EKTA parts listings, okay not exactly the same but completely different to the earlier 5 speeds which had a drain on the bottom of the casing and a fill/level on the LHS of the casing.

I had a quick look at my wife's August 2015 Polo 1.2TSI 6MT this morning and I've found that you can easily verify that there is another large hex plug on the LHS low down - as shown on the ETKA parts listing, so it definitely ties in with what is shown on ETKA in as much as "two identical plugs with a large hex socket head, one for fill/level and one lower down for drain, I can't comment on the base of the casing, but I'd be willing to guess that there will not be a drain plug there - again tying in with what is shown on EKTA listings.

[veteran]

Postscript:

It was around 1st November when I decided to write to three different companies that sell gearbox oil - Febi Bilstein, Fuchs, and Comma - following inconclusive replies to this Topic about gearbox oil used in petrol-version 6C/6Rs. It was only a few days ago that I finally received the last response from this set of companies.

Most of you will know that VW put their own formulation of GL-4 oil into the gearbox at the factory, and currently the VW specification for this is G-052-527. So, in principle, any third-party gearbox oil added after the vehicle's left the factory, has to, as a minimum, meet this specification.

The sorts of questions I put to these companies were:

1) Does their own product conform to, or even exceed, G-052-527?
2) How does their own product compare, in other respects, to the high-performance, longlife gear oil that VW puts into the current Polos at the factory, ie. the G-052-527 oil?
3) What other differences are there, eg. added dyes?
4) Given that, in recent years, the viscosity of this oil has been significantly lowered, how are the resultant issues relating to leakages and noise being addressed?

Just to remind everyone -

Febi markets a retail product referred to as 'Gearbox Oil 21829'.
Fuchs's product is called 'Titan Sintofluid SAE 75W-80'.
Comma's relevant product is 'MVMTF Plus 75W'.

All three fall into the retail price category of £9 - £13 per litre.

None of the companies answered my questions fully. And actually, although Fuchs initially acknowledged my enquiry (saying that they'd never heard of G-052-527!) that was the last I heard from them. I'll leave you to draw your own conclusions from that.

Febi replied that 21829 was the same as the OEM product. But they also said, "It shouldn't be thinner than G-052-527". But I never maintained it was. Irrespective, their comment doesn't really address the general mistrust surrounding the thinness of these oils now. They said they didn't know if the VW factory-fill was dyed or not. I was highly surprised at that.

Comma were the most forthcoming. They said that MVMTF Plus 75W meets with the VW specification G-052-527. Comma said that their product had been thoroughly tested (by whom?) and found to offer the requisite performance. Comma continued by stating that they couldn't comment on the additives used by VW but that they (Comma) used their own additives to give minimal friction and the required level of protection. Thinning the oil offered increased fuel efficiency and also helped meet the requirements of current environmental legislation. They said that it was common to find the OEM product priced significantly higher, but that some consumers were happy to pay that premium. Their closing advice was to always use a gearbox oil with proven adherence to the leading specification.

I'm still in two minds as to whether to get the OEM product in due course. But other than that, it's a clear choice between the Febi oil and the Comma oil. Instead of replacing the entire lot in the Spring, I might instead just drain off a litre or so, then top up with some new, clean stuff. The next time I'm at my local VW dealer's, I'll ask them their price for the oil and whether it's dyed or not.