MG4 Reduction Gearbox Oil Leak

[MSvirus]

Just another quick update for anyone that’s interested, I’ve just changed the diff oil again @ 56k miles.

it turned into a bit of a damp nightmare this time as the square drain bolt was seized/rusted solid and ended up rounding off, fortunately a “twist” socket extractor (lifesaver) worked a treat & bit into the soft drain bolt head. It was that seized I had to jack the wrench up to get it to start moving along with copious amounts of penetrating oil, got there in the end!

Anyhoo, once drained I got exactly 800ml of black oil out again which seems my car at least, will keep this level as this was exactly what I drained last time which is re-assuring, also very, very little swarf as expected now.

I was going to get the dealer to do this at the next 60k service but I wanted to know exactly how much came out / went in myself & decided as my warranty runs out at 60k ill most likely do anything using a local HEVRA garage for a stamp or myself going forward.

As looking at your drained oil, I would not be satisfied with that look on a drivetrain oil in that short period of time, considering this is not even the initial fill. You are not tracking the car? Do you live in a very humid place? It would equal to a 70W or 75W gear oil, which one is not good to know as the 150.000 cP dynamic viscosity temperature is not known. As being GTL oil I would guess 75W with minimum usage temperature of -40 degrees C (when the oil is new - not looking like that).

 

[tsedge]

As looking at your drained oil, I would not be satisfied with that look on a drivetrain oil in that short period of time, considering this is not even the initial fill. You are not tracking the car? Do you live in a very humid place? It would equal to a 70W or 75W gear oil, which one is not good to know as the 150.000 cP dynamic viscosity temperature is not known. As being GTL oil I would guess 75W with minimum usage temperature of -40 degrees C (when the oil is new - not looking like that).

My understanding is that oil colour does not indicate the need to change it - there are a number of reasons why oil can go black.

So far there's been no gearbox failures that I've heard of due to dirty oil, and the car has been out for 18 months now, plenty of time for high milers to stress the system.

I'll believe there's a problem when I see some evidence.

 

[MSvirus]

My understanding is that oil colour does not indicate the need to change it - there are a number of reasons why oil can go black.

So far there's been no gearbox failures that I've heard of due to dirty oil, and the car has been out for 18 months now, plenty of time for high milers to stress the system.

I'll believe there's a problem when I see some evidence.

Oil colour is not a valid criteria in ICE engine oils, in drivetrain oils where there is not molybdenum clutches (like from a LSD or an automatic transmission), oil which originally doesn't contain graphite or molybdenumdi/-tri sulfide, and the use of assembly lube is washed away with the first oil change, and the transfer of old oil to the new one on previous change is very low; usual culprits is high oxidation probably from very high temperature and/or high humidity contamination. Usually these drivetrain oils will stay like new for a very long period of time. Could certainly be interesting to see an used oil analysis of this used oil to better understand what criterium in these MG4 drivetrains that can make this effect. It will probably be a problem not for the first owner, more like the 2.-3.-4...

 

[tsedge]

Thanks for the explanation, that really helps put your comment in context.

Yes, be good to have some high mileage inspections and try to understand if MG need to shorten the period between changing the oil or if it will hold up for the long term.

 

[Tig170]

Just another quick update for anyone that’s interested, I’ve just changed the diff oil again @ 56k miles.

it turned into a bit of a damp nightmare this time as the square drain bolt was seized/rusted solid and ended up rounding off, fortunately a “twist” socket extractor (lifesaver) worked a treat & bit into the soft drain bolt head. It was that seized I had to jack the wrench up to get it to start moving along with copious amounts of penetrating oil, got there in the end!

Anyhoo, once drained I got exactly 800ml of black oil out again which seems my car at least, will keep this level as this was exactly what I drained last time which is re-assuring, also very, very little swarf as expected now.

I was going to get the dealer to do this at the next 60k service but I wanted to know exactly how much came out / went in myself & decided as my warranty runs out at 60k ill most likely do anything using a local HEVRA garage for a stamp or myself going forward.

Thanks for the update, my older car was a VW tiguan sport at 180k miles (do about 20k miles a year on personal mileage) - so never bothered with official warranties as such (unless it was a major fail - i.e. sunroof subframe weld fail / EGR cooler on the VW) - but did without fail change the oils / cambelt. Heat kills oil, so the only bit of worry (hence the post), was from the front diff oil, it was black on the VW at 120k miles. Thanks for the heads up, may just give our MG4 a quick oil change - I dont suppose you have the specs?

 

[spence7788]

Thanks for the update, my older car was a VW tiguan sport at 180k miles (do about 20k miles a year on personal mileage) - so never bothered with official warranties as such (unless it was a major fail - i.e. sunroof subframe weld fail / EGR cooler on the VW) - but did without fail change the oils / cambelt. Heat kills oil, so the only bit of worry (hence the post), was from the front diff oil, it was black on the VW at 120k miles. Thanks for the heads up, may just give our MG4 a quick oil change - I dont suppose you have the specs?

I’ve just been using the MG official oil (made by Shell but only available through dealers). It’s called SL2808, there’s a couple of pics I believe and a bit more on the specs etc. a few pages back the last couple of times I’ve changed it if you look at my past posts (today was the 3rd time) .

Yeah, I’ve always believed in preventative maintenance, this car is my main livelihood doing school transport & I knew I was going to have this well over the warranty period mileage (MG list price for the drive unit is over £8k alone!) & knew this was a possible weak spot (also we know how bad parts availability can be which is another concern for me) but for a lot of people I suspect they don’t care or will be rid of the car well before the warranty runs out!

If anyone is planning on keeping them long term I would definitely recommend, what harm can it do, on the other hand they may well be fine into big miles on the official 60k change schedule, I suppose a bit more time will tell.

As looking at your drained oil, I would not be satisfied with that look on a drivetrain oil in that short period of time, considering this is not even the initial fill. You are not tracking the car? Do you live in a very humid place? It would equal to a 70W or 75W gear oil, which one is not good to know as the 150.000 cP dynamic viscosity temperature is not known. As being GTL oil I would guess 75W with minimum usage temperature of -40 degrees C (when the oil is new - not looking like that).

Yeah, you sound more clued up on the mechanics & chemistry of oil than me but it probably comes across darker on pics, I mean it is dark but not like black engine oil dark in person.

The car has never been tracked but on occasion does get a hard short B road blast but generally lives an easy(ish) life I’d say doing school transport (2x 130 mile stints morning and afternoon) never at mega high speed but does most of them on A roads at sustained 55/65 mph so I imagine there is a bit of diff heat build up but I’m never cruising at high speeds.

The oil doesn’t smell burnt at all (doesn’t smell of anything really unlike the fresh stuff) as that was my main understanding of heat etc. unfortunately I’ve discarded it now otherwise I may have had a look at doing that out of curiosity, I’m not too concerned tbh as I change it quite regular etc. but I suppose time will tell how reliable these units are, with them being a combined drive unit there not cheap at all to replace!

 

[Macadoodle]

Thanks for continuing your updates spence, very interesting. Pleased that the revised factory breather is allowing 800ml to remain in the box, hopefully it's close enough to the apparent 900ml the unit was designed to hold that it won't make any difference.

Regarding the dark colour you're still noticing in your drained oil, it would appear that this is microscopic wear particles in suspension.
I left all of the oil I drained from my car,( I think 3 changes in total) on a shelf in my garage, and I noticed a couple of weeks ago that it has turned totally clear again having sat undisturbed since summer when I was messing around with my side entry breather idea. ( there's a thin band of dark stuff at the very bottom of the measuring jug )

Didn't think it was heat related as I never recorded a gearbox casing temp higher than 40 degrees IIRC.

 

[Les burrows]

Thank you it is good to know about it and the lack of swarf as you said reassuring you say warranty runs out at 60k why is that please?
Les

 

[Tig170]

I’ve just been using the MG official oil (made by Shell but only available through dealers). It’s called SL2808, there’s a couple of pics I believe and a bit more on the specs etc. a few pages back the last couple of times I’ve changed it if you look at my past posts (today was the 3rd time) .

Perfect, much apprechiated!

 

[MSvirus]

Thanks for continuing your updates spence, very interesting. Pleased that the revised factory breather is allowing 800ml to remain in the box, hopefully it's close enough to the apparent 900ml the unit was designed to hold that it won't make any difference.

Regarding the dark colour you're still noticing in your drained oil, it would appear that this is microscopic wear particles in suspension.
I left all of the oil I drained from my car,( I think 3 changes in total) on a shelf in my garage, and I noticed a couple of weeks ago that it has turned totally clear again having sat undisturbed since summer when I was messing around with my side entry breather idea. ( there's a thin band of dark stuff at the very bottom of the measuring jug )

Didn't think it was heat related as I never recorded a gearbox casing temp higher than 40 degrees IIRC.

If it is enough microscopical particles to colour the oil, then there has to be a great amount of it. The fallout of suspension can be a lot of different elements, since the oil used usually have lower density than 1, heavier elements tend to fall to the bottom, like moisture too. Used oil analysis is the way to go, even if that could fall short of counting the big particles. Are any of the dark stuff in the bottom of your jug magnetic? Some of the metals in the drivetrain is probably magnetic, but certainly not all. And what happens if you stir the jug up again?

 

[tsedge]

Thank you it is good to know about it and the lack of swarf as you said reassuring you say warranty runs out at 60k why is that please?
Les

I believe it is because of high mileage usage - well over the normal warranty limits that most people wouldn't breach. It is effectively a taxi.

 

[spence7788]

Thanks for continuing your updates spence, very interesting. Pleased that the revised factory breather is allowing 800ml to remain in the box, hopefully it's close enough to the apparent 900ml the unit was designed to hold that it won't make any difference.

Regarding the dark colour you're still noticing in your drained oil, it would appear that this is microscopic wear particles in suspension.
I left all of the oil I drained from my car,( I think 3 changes in total) on a shelf in my garage, and I noticed a couple of weeks ago that it has turned totally clear again having sat undisturbed since summer when I was messing around with my side entry breather idea. ( there's a thin band of dark stuff at the very bottom of the measuring jug )

Didn't think it was heat related as I never recorded a gearbox casing temp higher than 40 degrees IIRC.

Thanks Macadoodle, that’s really helpful mate, I wish I hadn’t discarded the old oil now, think I’ll get an analysis done the next time & see what’s in there, at least it’s highly unlikely heat with your findings and lack of burnt smell.

I believe it is because of high mileage usage - well over the normal warranty limits that most people wouldn't breach. It is effectively a taxi.

That’s right Les as tsedge mentions it’s the taxi warranty unfortunately, it’s down in black & white where you guys should be good for 100k on the drivetrain & battery.

Out of curiosity I enquired when getting the service parts a few weeks ago re drive units, there was actually one available in the country to my surprise, I forget the exact figure but with vat added you wouldn't get much change out of £9k! Plus god knows how many hours labour on top.

(the couple I’ve heard about being changed also needed updated software to avoid any problems or “mate” them properly effectively) so it would most likely have to be an MG dealer job) hence trying to look after mine)

May be overkill for many but I’m contemplating for my situation and peace of mind if I find a used unit form a car being broken at a half reasonable price to keep as a spare effectively!

Long live the diffs!

 

[MG4London]

But should you need to do that? A brand new car that should be under warranty shouldn’t it?

 

[siteguru]

Perhaps read back a few posts ... @spence7788 is using his effectively as a taxi, so warranty limits are different.

 

[Les burrows]

I do not understand why a car that as a 7year 100.000 mile warranty is only getting 60.000 because it’s used as a taxi bit unfair that for me.
Les