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Hi!

I've decided my gearbox oil is in need of changing, as sometimes when warm selection, particularly into fifth can be a bit sticky. Its not a linkage issue as it selects fine when cold, its just I think the oil has got a bit worn out over the years.

I know its a pretty straightforward job to do, but I wondered if anyone could give me a step by step run through of it? Are there any special tools needed to do it?

Can I get the oil from GSF?

Thanks!

Tom

You'll need a 17mm hex bit to get the drain and filler plugs undone.

Use oil to SAE 75W90 spec, or API-GL 4/SAE 80. I've previously got mine from my local motor factors, though if you get stuck Esso filling stations have the right stuff. For my current 'box I went to VAG and got 4 litres (you need 3.1) for just over £18.

When I refill a 'box I do it through the speedo drive hole, with the filler plug on the side of the 'box undone. When oil starts trickling out the filler plug the 'box is full.

Try not to get it on yourself either, it stinks. It REALLY stinks.

Good idea there, Andy, to prevent overfilling. It's quite easy to overfill, as you cannot tell where the level is when filling it through the normal fill hole, with the tube in the way.

What I did was just overfill it, then leave it for about 15mins for the excess to drain out. When it stops flowing out, the level is exactly at the bottom on the filler hole, where it should be.

LogIK wrote:What I did was just overfill it, then leave it for about 15mins for the excess to drain out. When it stops flowing out, the level is exactly at the bottom on the filler hole, where it should be.

And your garden, patio, (or back street and drain in Alex's case) reek of cat p***! It's an unavoidable stench.

I've got to take my G40 'box off tomorrow and drain it to fit new oil seals. My old clothes and parents' garden are going to stink again...

Citrus fairy liquid poured on the driveway and scrubbed does a good job of removing oil spills and gets rid of the stench

its pretty easy - i found the main problem was lack of reliable info making it look harder than it was.

STUFF
* First up you need to find a 17mm allen style socket bit, and a suitable wheel brace / torque wrench / socket driver / rachet to use it with. Needs to be fairly sturdy as you may need some oomph to "crack" the nut with - odds are it hasnt been moved for the best part of a decade and might have some external rust holding it shut. Will be pretty smooth once you've got it moving though.
* Then, THREE one-litre / US quart bottles of 80w90 gearbox oil, for the 4-speed anyway. 5-speed might need four bottles. Add an extra one if you wish to flush it through "properly". They're not earth shatteringly expensive.
* A bucket of warm water, preferably one that can be refreshed when it cools some.
* A length of discarded (or, "discarded" ) garden hose, call it 1 metre for argument's sake. I used the same one I keep for inserting spark plugs with the haynes "thread preserver" method.
* A funnel. Bigger the better, so long as it will fit in the hose.
* A catch tray - obviously, enough to hold 3 litres.
* Lots of paper towels.
* Rubber gloves if you can spare 'em.

DOINGS
* Preferably, take it for a real gear-whirling thrash beforehand to warm the stuff up (same as you might take a 5 minute cruise before changing engine oil, but you want the gearbox to get hotter if possible, rather than merely warm). In my case this would probably consist of just sticking it in 4th and belting one way up the M42 then back again - this always seemed to affect the shift in such a way that could be explained by thinned oil.
* Put a quantity of paper towels under and around the gearbox and lay the tray on top.
* Use the allen bit & socket wrench to first undo the TOP bolt on the side of the gearbox. It's about 2/3 the way up the housing, fairly obvious once you've brushed some of the grot off. May help to dig the dirt out of it's inside edges. (Top one first, because if you undo the bottom one and then find the top one is jammed, you are SCREWED).
* Undo the bottom one (still on the side, but lower down) and watch all the old oil slowwwwwwly splurt out with a contented, buddha-like smile.
* Replace the bottom bolt.
* Insert one end of the hose into the top bolt hole and make sure it's in snugly but doesn't dip too low inside. Have the top end poke up out of the engine compartment and jam the funnel in the top. If it's stupidly high, chop the hose down to a more sensible size with heavy duty scissors.
* Assemble the bucket of hot water (hotter the better but dont scald yourself) and float the bottles in it. Give them 5-10 minutes. Replace water if it cools too fast. (At about 50 celcius the gearbox oil is still as thick as 10w40 in winter - it's like treacle at room / british summer temps and will not flow very well at all - this may be noticed when you are waiting for it to empty)
* If properly flushing the box, undo the bottom bolt at this point and run a whole bottle down the hose. It may seem wasteful, but the oil has probably never been changed before - and although it doesnt pick up tons of carbon deposits every few thousand miles like engine oil does, the sludge left at the bottom when empty will still be chocka with metal swarf from the gearteeth, synchros, reverse gear, ground dog clutches after botched changes, etc. Best to try and push some of it out rather than letting it swirl up into the new oil.
* In either case, make sure the bottom bolt is on tight, and tip in the other three bottles until oil starts leaking out of the top bolt hole. Go easy with the final bottle.
* If you wish to still try a little flush with a minimal bottle method, try to guage how much you have left, and carefully, holding your finger against it to stop it flying off, undo the bottom bolt again, to release that much minus a few spoons into the catch tray before re-tightening it. Top the level back up again.
* Replace and tighten the top bolt and check the two are both firmly in place.
* Take it for a gentle ride to make sure everything still works alright.
* Resume normal driving.

Note that I didn't mention jacking it up - the whole procedure can be done from above, or mostly above and partly below without a jack, if you're careful and/or jammy - and it will both drain and refill best if done with the car completely level. A garage would use a 4-wheel lift - we have to make do with jamminess and taking advantage of conveniently placed parts i.e. the bolts (a long handled torque wrench helps)

Good luck....

that is exactly what I wanted Tahrey1043, thank you!!

I shall have a go at it tomorrow methinks. Once I've done it once it can't be that hard. Just need to get a 17mm hex key from somewhere.....

There's no need to heat the fresh oil up to pour it in BTW, never had any problems tipping it in as it is and I've done it several times now! Also - if you're worried about flushing it, don't use fresh gearbox oil - get some thin and cheap engine oil (supermarket s**t is ideal) and use that to flush through. If you're feeling really keen you can take off the 5th gear end coverplate and scrape out and s**t that's accumulated in there.

And seriously, fill through the speedo cable hole - it's a million times easier!

Maybe not in this summer heat mate (almost as warm as the water would be), but certainly at the time I did mine, which was about late jan to early feb, the stuff was resembling particularly thick golden syrup. Like I was having to squeeze the bottle to make any come out - and that was after storing it in the house. A few minutes float in some hot-tap goodness made it a lot runnier and easier to handle.

Think the old stuff actually came out quite easy though - after all that time its understandable it might have "sheared down" a bit and become looser (such as engine oil supposedly does after a mere 5k)

Top tip on the engine oil to flush with, rather than the GB stuff - i remember that advice from some other time but had forgot. Much more effective. (I think that's actually what I used when doing mine 14 years, 81000 miles and a lot of abuse = for the best to give it a run-thru with some cheap 10w40... even better, tescos value 20w50 (cortina juice ) for 89p a litre)

speedo cable tip i wish i'd known, but doesnt that give you a much smaller gap to aim for? or will it accept a funnel?

If you remove the speedo drive totally (22mm spanner/double depth socket) it's a nice big hole for the funnel to fit in - miles easier! If you really wanted to clean the s**t out you could put through a few gallons of petrol, but I offer no guarantees on 'box seal life afterwards. Thin s**t engine oil is miles safer.

I know where you're coming from on heating the oil up, but I've filled them up over winter too (my gearbox woes started last December) and it's fine as long as you're patient. Interesting to note that the genuine VW 'box oil I used yesterday (no gradings or any info on the bottles BTW) was a lot thinner than the supposedly within spec 75W90 oil I'd used previously.

ha well one thing i definately wasnt was patient, as i was intending on driving the car somewhere later that same evening!

an oil (optionally + filter + airfilter) change of any type that takes more than a half hour smacks of laziness to me which is why i wanted to speed it up
(which is why i was so peed off at whoever put the ashy's last oil filter on - I had to drive a chisel through the bugger with a mallet in the end and grab BOTH ends to torque it off. then the airbox was a nightmare too. whole operation took hours when had only budgeted 40 mins!)