Mixing automotive fluids is generally neither necessary nor recommended. However, people do mix fluids for various reasons, and I'm curious about possible unexpected results, such as precipitation and foaming. Here are some examples:
Automotive fluids (motor oil, gear oil, atf, hydraulic oil, etc.) consist of base oil, an additive package, and possibly viscosity index improver. Additive packages are carefully formulated, as individual additive compounds may interact synergistically or antagonistically, and may even function differently depending on the base stock. Mixing automotive fluids of different types produces an oil of unknown viscosity and performance properties. Presumably, the base oils would mix amicably (right?), but "mixed" additives would offer different levels of protection and the "mixed" VIIs would function differently than intended.
However, what would cause a mixture oil to exhibit odd behavior such as foaming? Has anyone actually observed this result? Is additive precipitation another possible outcome? What else can happen (besides altering the fluid's effectiveness)?
I mixed [hydraulic fluid and ATF] in our lift at work and it foamed.
...if you mix gear oil with motor oil ..you'll get spontanious foaming.
Automotive fluids (motor oil, gear oil, atf, hydraulic oil, etc.) consist of base oil, an additive package, and possibly viscosity index improver. Additive packages are carefully formulated, as individual additive compounds may interact synergistically or antagonistically, and may even function differently depending on the base stock. Mixing automotive fluids of different types produces an oil of unknown viscosity and performance properties. Presumably, the base oils would mix amicably (right?), but "mixed" additives would offer different levels of protection and the "mixed" VIIs would function differently than intended.
However, what would cause a mixture oil to exhibit odd behavior such as foaming? Has anyone actually observed this result? Is additive precipitation another possible outcome? What else can happen (besides altering the fluid's effectiveness)?