VT Commodore - Oily / Cruddy / Dirty Coolant

[Anglosaxon]

mine looked very much like that and it was trans fluid, often with a hairline crack in the trans fluid gallery in the radiator there will be enough pressure in the trans fluid to force it through the crack into the radiator but not enough pressure in the water to force water into the trans fluid line, and the trans fluid forms a really weird coloured emulsion in the radiator water. I noticed a bit in my radiator reservoir one day and thought what's that then an hour later it overflowed the reservoir, gunk everywhere, pumped all the trans fluid out into cooling system but not one drop of water in the trans.

 

[gregaust]

A pressure test of the cooling system would be my first check, if it holds on then a flush and go from there.