Time to change gearbox oil?

[osx]

Dont think this has ever been changed (unless it was done when they changed the flywheel 2 years ago).

Will this do

https://www.gsfcarparts.com/za042779?au ... KYQAvD_BwE

What is the required volume? Do I need to reset anything in Diagbox once done or it doesn't matter as it's not supposed to be serviceable ?

[CitroJim]

Unless you have a leak, there's no real need to frequntly change the gearbox oil... It lasts a long time as there's noting really to contaminate it...

If you are concerned, drain a small sample and look at it. If it still looks nice and clean and clear it can go on a while longer...

Often the oil is changed by necessity when driveshafts are removed/replaced as doing that will unavoidably drain most of the oil... It's never a good idea to reuse what's drained out during driveshaft swaps as its highly likely to get dirt in it whilst draining.... When you had your flywheel done, it would have been changed for sure.

The oil you link to should be OK if it meets the specs. laid don by PSA for your particular 'box... 2 litres or so is the usual amount...

That's for a manual 'box. In the case of an auto I believe regular changes are beneficial as considerable friction material accumulates which can start to plug the filter...

That's my view, others may hold differing views

[osx]

If it was done with the flywheel then I'll leave it.

[Tilly]

same as above....As long as you have been meticulous with cleaning up the drain plug area, and drained your oil into a clean container, you can reuse it if its recently been recently replaced. Otherwise, I'd replace it. They are supposed to be sealed for life, but thats just put out there for fleet sales to be honest. Dont listen to people who claim, just because its not black, its ok. Theres no combustion process to carbonise the gearbox oil, but it does get "tired" over time, or gets contaminated with water. Replacing it costs little, and gives you peace of mind its been done.

[MattBLancs]

I too am in favour of manual gearbox oil changes.

Lots of good points raised here, but also of note is that the gearbox oil also accumulates a lifetime of metal fragments, wear from syncho rings, selector forks etc.

Yuk!

This is the old (and new) oil from my C5 X7. I thought it was original but will check service history as had gearbox off in the past, so may be less than 13 years / 140,000 miles use as pictured.

I've bought 75W80 in 5 litre bottles (enough for two gearbox changes) and makes me feel better for having changed it, if only the placebo effect!

[CitroJim]

As an addendum to my original post, I was convinced I wrote that a good change interval would be five years for the reasons you speak of Matt... Seems that point was lost in my editing of said post

You just can't get the staff these days

You are of course absolutely correct

Generally, I reckon that in those five years, driveshafts will have been in and out so the oil change interval will happen by default anyway

[MattBLancs]

I've lost stuff I've typed too Jim - usually distracted then come back to submit it and get the log on screen instead. Sometimes I can hit Back and then copy all I've written, sometimes that doesn't work.

I'm not sure if time or mileage is best for defining when to change but "all change is good"


I have reused gearbox oil often, I know it's hypothetically possible to interact with the front left hub without the driveshaft popping out on a BE gearbox, but don't think I have ever actually achieved it!
I've tried "be careful" numerous times and still find a "little smelly puddle" appears part way through. So instead now routinely drain box oil via drain plug and no longer need think about driveshaft position!

If if looks like the above grim muck: it'll get changed, otherwise topped off and poured back in (normally via the vent top of the box rather than the level plug which is a faff to access, keep car level etc when working axle stands on driveway) funnel and short length of hose pipe coupled together just for that job.

[CitroJim]

I know it's hypothetically possible to interact with the front left hub without the driveshaft popping out on a BE gearbox, but don't think I have ever actually achieved it!
I've tried "be careful" numerous times and still find a "little smelly puddle" appears part way through. So instead now routinely drain box oil via drain plug and no longer need think about driveshaft position!

Ditto, however carefully I've tried I also drain fully now but only on one occasion have I ever reused... That was on a Xantia where one of the driveshaft seals supplied for me to fit was the wrong size... Only noted when refilling the 'box 'Box was spotless just after a clutch job and so was my drain pan

[MattBLancs]

Yes, clean drain pan (or 3 litre Vimto bottle as above - washed out, dried out of course! ) And around where the drain plug sits. Take the drained stuff well away from the rest of the job and covered till ready to feed back in. (To remove chance of the oil gaining lumps of rust, road muck, grinder dust etc!)

I've often started a job then find other stuff needing seeing to "on the way" (that invariably I have not got "in stock") so it's not always that long between draining sessions - so lots of drain and refills for me!

It's worth noting I generally plan in box oil replacement for whatever the first job a new-to-me car needs that has me working in that area (and what comes out has never, ever looked fit to reuse on that first change!) - so the oil I might consider reusing will always only be as old as how long I've had the car.

This "first change" has expanded to now include driveshaft seals as these are so cheap it's daft not to change them too.

The C5 was treated to a new gearbox input shaft too with its "first change" but only as box was coming out for the (groan, concentric) clutch slave cylinder which was first job the car demanded.

[Estately]

Since nobody else mentioned it, a strong magnet placed on the drain plug for a couple of weeks driving about prior to the oil change yielded (iron) filings and paste.
The car came with a factory fitted tow bar and so at about 60k miles I decided to change the gearbox oil not being sure how much towing it had done.
The oil was heading for a black colour so I thought it was worthwhile.
Hope that helps.
Andy.

[MattBLancs]

Magnet idea is good one, I like that.

Bought a cheap magnetic drain plug for but had not appreciated how long the magnet was and how close the crown wheel teeth pass by the drain hole! Spotted before tried screwing into place (but after oil was out the box of course!) Filed in the garage under "might find another use for it"

[Jay-Bruce]

Even if it retains it's new colour and clean appearance, in a gearbox application, oil's long chain polymeric hydrocarbon chains shorten as the molecules are subjected to steering loads, thus lowering it's either it's thixotropic rheology and or it's general viscosity. I don't know if you've ever ran a car on or a forklift on LPG, but the oil in those engines seemingly lasts forever, in that it never gets dirty, but by the third service interval not being changed because it still looks clean, it's got the viscosity of whisky and possibly worse than whisky as a lubricant. So yeah, I'm with Matt on this one, do it.

[CitroJim]

Most gearboxes I've seen have magnetic drain plugs as standard fitments...

I've seen some very impressive 'hedgehogs' living on them in the past, especially from ZF 4HP20 autoboxes...

Jay, yes, in engines, no argument at all on oil change intervals irrespective of what the oil looks like!

I'd have hoped that good quality oils intended for gearbox applications enjoy the benefit of higher quality more sheer-stable VI improvers than engine oils do, given they are expected to survive for a long period in gears that look like knife blades to polymer VI improvers... I believe the base oil is of a higher viscosity so there's much less need for large quantities of VI improvers in the oil compared to a wide-range engine multigrade oil.

My experience of the multitude of manual boxes I've drained is the oil oil comes out thicker than the new stuff going in...
This can considerably improve the gearchange quality in BE and MA boxes!

[MattBLancs]

Most gearboxes I've seen have magnetic drain plugs as standard fitments...

Interesting Jim, I'm pretty sure the BE gearbox drain plug (that I intended to swap with my too long magnetic eBay special) was not magnetic, certainly not strongly so anyway.

Think BE gearbox and ML both have a coin shaped magnet inside the casing. Presumably this is a great item for gearbox rebuilder to withdraw from the box and show the customer why a rebuild was not a waste of money!

The (very unwell) AL4 gearbox I took to bits had a good hedgehog on its magnet!

[CitroJim]

I've got some photos of HP20 hedgehogs somewhere Matt, I must dig them out... One from one that died quite violently. It's spectacular...

They have internal magnets all over the place... Maybe it's the older 'boxes that have a magnetic drain plug? I know both the MA 'boxes in my AXs have...