Transmission Fluid Change DIY

[JCL]

Originally Posted by mbk

I can't believe that. That would be paramount to fraud... A company can't out rightly say a specific product is for something specific if it isn't. There are stringent tests these oils have to go through to get on the market and they have their specifications listed and out for everyone to see. They have obviously been viewed, compared, and trialled for suitability.

Typical Characteristics: SYNATF
KV @ 100°C, cSt 7.000
KV @ 40°C, cSt 33.40
Viscosity Index 179
Density @ 15°C, g/mL 0.8514
Pour Point, °C

These must lay within the parameters for that oil and therefore it has been deemed "suitable" for that application

You are incorrect. All transmission fluids are essentially just light weight hydraulic oils. Those specs above are generic. What makes the various fluids unique is the additive package, essentially friction modifiers that impact how the wet clutches engage. Those are proprietary. They are matched to the control algorithms and designs of each transmission. The specs aren't openly published. The holder of the spec, ZF in this case, will supply the details, and test any oil for someone who wants to license it and pay that fee. Anything else is close to a 10w hydraulic fluid with unknown frictional characteristics at the clutch plate interface.

We know that some specific fluids have different enough boundary layer frictional characteristics that they result in failures when used in specific transmissions. Yet this fluid claims to be suitable for both those applications. That is the quick test of whether it is a reasonable claim.

It isn't fraud to say that something is suitable for vehicles that call for x. There is no stated guarantee of it being fit for use. It is fraud to say that it is x. That is why the lawyers review those marketing claims. It is legal, but questionable.

You are completely free to make your own judgement. Using a non-spec fluid won't guarantee failure. It just introduces an additional risk factor to a procedure that already has risks.