Technical Transmission fluids query (another one, I apologise now...)

[Jamie KC]

Have a transmission fluids question. I've used the forum's rather good search search function, so I can see that it is one which has been asked many times before, but there seems to be differed or inconclusive answers... Also aware that there is no need to change them at this mileage, but will do to try and resolve/eliminate them from my transmission noise issue.

Panda 4x4 MJ 2014

Gearbox oil - No confusion, just use synthetic GL4+ spec.
PTU - Needs GL5 (Tutela Multiaxle Fiat 9.5550-DA3)
Rear diff - Needs GL5 too. (Tutela Cross Fiat 9.5550-DA4)

I've seen a couple of suggestions that you could in fact use the same oil for the PTU and the rear diff as both are GL5 spec.

At risk of sparking a some more differing answers I thought I'd ask again! Opinions please - Does this seem sensible? If yes, which fluid to choose? And why , or why not...

 

[Jamie KC]

Have also seen on here that the gearbox in these vehicles would benefit from Molyslip, in which case I assume the rear diff would likely feel the benefit too?

 

[The Panda Nut]

No oil is sutable for sealed for life use. None!!! Having had a gearbox start to die in my Bravo at 100K I regret not changing the oil in it. Iwill be changing all the fluids in my 4x4 at around 30K. This to me is a no brainer.

I looked at gearbox oil specs when our 1.2 change became a bit stiff. On the 1.2 there are two typres of oil. The older cars have a very slightly different grade this seemed to be something to do with the sulphur content. I decided to get the Tutella recommended oils and changed both cars. The older car was hugely better for the change and the newer one better but less obvious. Itw as at a lower milage though, 30K as opposed to 50K. I hunted on the internet and managed to get the Tutella oils for a good price, much the same as any other type. There were large price variations from different suppliers.

I like to stick to the exact oil recommended as I dont know if there are subtle differences that ,make a difference. Common sense says that any oil of the correct specification should do a prefectly acceptable job. Years ago it was usually EP80 or EP90 and any oil oil would do. Better gearboxes need better oils so the right grade is important.

I have a TA 4x4 and I would definitely stick exactly to the specified oil for the transmission in that. There are too many variables in the control system to risk anything changing its equilibrium!. You dont want to upset some sensor because the oil slows down the 4x4 engagement. Its just not worth it.

I have used moly additive in a couple of gearboxes over the tears and found it seemd to make things run smoother and quieter. It never caused any issues but some of the more knowledgable engineers on here suggest its not a good thing for technical reasons due to altering the friction levels and what this can do to synchro operation. Unless the box is awkward I would think carefully before adding to a modern gearbox. The 4x4 gearchange is not the smoothest in the world but its a 4x4 so a racing change is not really in keeping?? If you do use it please let us know how you go on. Being super conservative I havent experimented with alternatives. In my time I have busted many gearboxes and diffs I think this influences me.

Finally I am unconvinced that Tutella is the best available, but the scince behind oils these days and the methods of classification is such that we will never know. The extra money on the right oil is very very small beer comapred to a geabox repair.

 

[Herts Hillhopper]

Worth pointing out (for those who don’t already know) that the diesel 4x4 has three separate oil-filled units, but the TA only two (the latter combines the gearbox and transfer unit - that sends drive to the rear - in one casing, so it’s an easier choice

I suspect some of the reason for three different specs (one for each unit) relates to the age of the design of each part. The 5-speed gearbox on the 4x4 Panda has been used by many vehicles over many years and so the spec is old too.

The little PTU unit on the MJ 4x4 is unique to that car, and a newer design - hence a more up to date oil spec (the GL5 spec being newer). To me, I can’t see why the fluid for that can’t be use in the rear diff too as the basic viscosities are the same.

Trouble is it’s really hard to find that ‘genuine’ fluid. I refilled my PTU with an alternative that met all the same specs - I’ll look up my earlier post to remind myself what that was

As to the brand of oil - really that shouldn’t matter. It’s interesting to look at which marque recommends what. Fiat has a link with Selena (they used to own that company, but no more - it was bought by Petronas). Renault always recommend Elf (two French state-owned businesses). Ford say Castrol, but the identical engine is a Peugeot says it should be Total Oil. Toyota don’t recommend a brand at all, just the basic viscosity figures…

 

[Jamie KC]

Thanks gents. As anticipated, more differing opinions

@Herts Hillhopper, I searched and it seems you used

”Fuchs Titan Sintopoid FE SAE 75W-85 Fully Synthetic Gear Oil”​

Being a full Sun GL5 oil of the right viscosity it ought to be fine for both. The tricky bit is knowing what the two different Fiat spec numbers mean and why they chose to use the two different fluids.

My gut says use a good GL5 oil for both. My brain says there must be something in the differing factory spec…

 

[roverp480]

Thanks gents. As anticipated, more differing opinions

@Herts Hillhopper, I searched and it seems you used

”Fuchs Titan Sintopoid FE SAE 75W-85 Fully Synthetic Gear Oil”​

Being a full Sun GL5 oil of the right viscosity it ought to be fine for both. The tricky bit is knowing what the two different Fiat spec numbers mean and why they chose to use the two different fluids.

My gut says use a good GL5 oil for both. My brain says there must be something in the differing factory spec…

Having worked in the Motor industry these seemingly odd variations are often caused by the fact the original testing may have been done with different oils ,due to timing and changes in policies. Due to cost & time constraints the engineers wont do a whole batch of new tests just to check a later oil is OK and the lawyers due to liability issues wont agree to just changing the specifications without testing .

 

[Herts Hillhopper]

Having worked in the Motor industry these seemingly odd variations are often caused by the fact the original testing may have been done with different oils ,due to timing and changes in policies. Due to cost & time constraints the engineers wont do a whole batch of new tests just to check a later oil is OK and the lawyers due to liability issues wont agree to just changing the specifications without testing .

Yea, that’s sort of what I meant… old vs new, and newer might be better

 

[Jamie KC]

Having worked in the Motor industry these seemingly odd variations are often caused by the fact the original testing may have been done with different oils ,due to timing and changes in policies. Due to cost & time constraints the engineers wont do a whole batch of new tests just to check a later oil is OK and the lawyers due to liability issues wont agree to just changing the specifications without testing .

Makes sense.

Thanks for the various inputs. I'll go for the same GL5 oil in the PTU and RR diff, stick with GL4+ in the front end, and swerve the additives.