Gearbox oil change, why or why not?

[nielshm]

I just had my wifes Aygo in for a 7 year oil change. Milage is 105.000 km.

I asked if I could have a gearbox oil change. We'll, we would'nt recommend it, the garage said. Toyota says it never needs to.

I insisted, and had it done anyway. I can't tell any difference, but it feels good to know, that the gearbox won't suffer any problems related to old oil or slugde.

Why is it, that gearboxes never need service?? Car/engine service every 15.000 km., gearbox never. It's a cheap fix, less than 2 liters, same price as engine oil, and only 30 min. work. 

 

[flash22]

both the manual and mmt are manual gearboxes, lack of maintenance can cause issues with 5th and 4th Inc synchros

it's a very simple job, but make sure it has been done

i will have to look up the service schedule for the Aygo - have it here somwhere

[Mooly]

Gearbox oil only suffers from 'mechanical wear' at a molecular level... it does happen but only very slowly as the individual molecules get exposed to extreme pressures and shear forces in use. In practice it means it lasts a long long time.

Engine oil gets quickly contaminated with combustion products and dilution from fuel plus it is also exposed to extreme temperatures such as oil jets lubricating the cylinder walls. This is why engine oil turns black and sludgy over time.  

 

[flash22]

Moisture can be an issue too

normal use it says inspect at 60,000 and 90,000 km, replace if required, same again at 48-month intervals

knowing the 5th gear issues, it's better to be safe than sorry gearboxes do get a thrashing with the little 1kr engine

[TonyHSD]

Very important to use exact same spec oil and preferably Toyota genuine oil. 

[Yugguy1970]

As no oil is made of magic, all oils will degrade over time.

Also for manual gearbox there's no dipstick so it's not uncommon for cars to be running on little or no oil, as it's very hard to check.

[Guest]

I did this in 2016 on a 2005 Fiat Panda 1.2. It was feeling a little rough with the gear changes (synchro is what I remember reading / thinking was wrong at the time). It was hard to find, but the genuine proper Italian stuff the book said is what I ordered from a specialist. Not cheap either!  It made no real difference to the feel of the gear change.

I'd say at 7 years it won't do no harm. There is bound to be tiny metal bits from the friction of the gears and parts inside over those years - whether or not they'll do another harm for the next 7 , or 14 years is probably debatable.

But if it were my car I'd do it. I'll be doing it on my Avensis so long as I can find the kind of oil when it gets to 7 or 8. 

As Scotty Kilmer says "oil is cheap, engines are expensive" same surely applies to the gearbox.

If you get Toyota to do it, make sure it is done as said above

[Cyker]

Changing the gearbox oil is also adds the potential for the garage to bugger something up - I'm sure the oil change contributed to the destruction of my old Mk2's gearbox as they used a multiweight oil and I'm sure it is supposed to take a single weight oil. They insisted it was the correct oil tho'.

[TonyHSD]

7 minutes ago, Cyker said:

Changing the gearbox oil is also adds the potential for the garage to bugger something up - I'm sure the oil change contributed to the destruction of my old Mk2's gearbox as they used a multiweight oil and I'm sure it is supposed to take a single weight oil. They insisted it was the correct oil tho'.

The multi weight oil is superior to the single weight but if they put the wrong spec like GL-5 where GL-4 is required then the oil might had been the real reason for the issue. 👍

[Cyker]

It depends what you mean by superior - In this case IIRC they put in 75w90 but I think it should have been straight 75. Because it was 75w90 I suspect it thickened too much and didn't lubricate properly when it warmed up which contributed to the problem. (Likely wasn't the sole cause of the problem as I could tell the gearbox was already having trouble before it was changed, but it probably tipped it over the edge!)

 

[flash22]

75w90 sounds about right that age of car to GL4 spec

[TonyHSD]

55 minutes ago, Cyker said:

It depends what you mean by superior - In this case IIRC they put in 75w90 but I think it should have been straight 75. Because it was 75w90 I suspect it thickened too much and didn't lubricate properly when it warmed up which contributed to the problem. (Likely wasn't the sole cause of the problem as I could tell the gearbox was already having trouble before it was changed, but it probably tipped it over the edge!)

 

It will provide better protection at wide range of high temperatures where the single grade 75w only at specific temperatures, basically the multi weight oil is better one. 

[nielshm]

But why does Toyota have a major focus on keeping the engine trouble free with 10.000 miles intervals, thin oils for cold start protection (and mpg increase)? My Corolla gets a sevice/oil change every 7 months, thats a lot in a 8 year ownership.

But the gearbox never requires anything. I think the serviceplan listed in the manual goes up to 160.000 miles, oil change is never going to happen, maybe a inspection at 100.000 miles.

And what is lifetime in terms of oil? My lifetime? The cars lifetime? The gearbox? If the gearbox breaks down after 5 years, and the car has done more than 160.000 km, I guarentie that nothing will cover the cost is takes to make a reapir or replace.

[Guest]

2 hours ago, nielshm said:

If the gearbox breaks down after 5 years, and the car has done more than 160.000 km, I guarentie that nothing will cover the cost is takes to make a reapir or replace.

... and proof of change of gearbox oil will make no difference to that.

17 hours ago, Mooly said:

Gearbox oil only suffers from 'mechanical wear' at a molecular level... it does happen but only very slowly as the individual molecules get exposed to extreme pressures and shear forces in use. In practice it means it lasts a long long time.

Engine oil gets quickly contaminated with combustion products and dilution from fuel plus it is also exposed to extreme temperatures such as oil jets lubricating the cylinder walls. This is why engine oil turns black and sludgy over time.  

As Mooly correctly points out engine oil is subject to major causes of oil degradation from fuel contamination and temperature but gearbox oil has a more 'benign' environment of only pressure and shear force (which oils are designed to 'live with').

[Yugguy1970]

Not quite the same but I changed the rear diff fluid in my 2008 C class, it was 10 years old at the time, 53k.  The old stuff was discoloured and I swear the diff was a bit quieter.

But it cost me about 50 quid to do all in, including hiring a car lift for a morning to make it easier, so it was worth it.

[Hornet3D]

I don't think I have ever changed the oil on a gearbox, or had it changed either.  When I was working I was commuting a lot any more than a few of the cars I owned sailed past the 100,000 mile marker.  Now I am retired I do nothing like the same mileage so I can't see my routine changing much.

[fossyant]

Gearboxes wo't need oil unless you have a leak. MY Nissan is on 140k miles and has never had agear oil change. The Aygo is on 100k and I doubt that's ever had any - gear changes are slick and light.

[planc]

Toyota gear box oil replacement intervals used to be 40,000 miles/4years.

I think it is recommended to check the oil quality at 40,000m / 4years now.

For what it costs to replace 2.5-3L of oil it ain't with risking it.

[Red_Corolla]

It doesn't do any harm and can help by removing any loose metal particles, although I would expect a Toyota gearbox to be equipped with a magnetised drain plug. I think some manufacturers started doing away with the magnet as a penny pinching measure.

[TonyHSD]

I had some cars that are old and never had transmission fluid change and no trouble at all. I do however change on my hybrid every 60-80k miles, it’s a a simple drain and refill process.
The first change at 80k miles the oil was darker than the new one, the second change at 140k miles oil was better than previous time and my last change few weeks ago at 200k miles the oil was very similar to the new one as general appearance and smell. So far so good. But if you are not putting the exact same spec oil better not to change it at all. 👍