Commercial rubber roof .. leaking oil???

Motor oil? Water from a roof leak will often have a tea color, but it's viscosity will still be that of water. I'm guessing you have a standard run off the mill roof leak.

I know it sounds weird, but the liquid was the viscosity of something between water and used motor oil ..and probably about the color you would expect from such a mixture. I wondered if maybe the rubber roof was put down with some kind of petroleum-based adhesive that was breaking down. When I looked across the puddle on the floor, it even had the rainbow effect like an oil and water mixture. And I had to soak it up using oil absorbent (it generally would not evaporate, but where it did there was even like a black bakelite/charred type of residue).

There will be some oils from a newly applied roof that water will pick up. It could be enough to cause the sheen, but I can think of anything that would cause a viscosity change. Still, if this fluid only appears around outside precipitation, I'd say common leak. If not, I have no idea.

=================================== Not the rubber, nor the rubber cement they used .. if it was correctly applied with authorized materials. It is possible that the rubber was placed over an existing asphalt surface? What you are describing fits perfectly with describing a piece of ordinary asphalt shingle sitting in mildly acidic water, such as rain.

I just had a rubber roof installed on house & porch & next morn porch was covered in oil! Have no idea whar caused it but rubber was put over asphalt.

did you ever find out what it is. our business is having the same issue. oil is dripping from roof deck. Resembles used motor oil like you said. we have had the roofers out 2 times and they say there is nothing wrong. oil leak is no where near any mechanical, fire or plumbing (50+ feet).

Is there an air conditioner on the roof if so the compressor fluid might be what you are seeing if it hasn't been properly changed it can leak out the clutch housing

Cars aren't hermetic. Is there a car on the roof?