1N4728 Zener behavior
Source: TL082 datasheet.

The absolute continuous ratings for the TL082 state that the output short-circuit duration is 'continuous'. This means that there is current limiting built in. The low output impedance you quoted is conditional on the output stage not being overloaded. 

Looking at Figure 7 the positive current limit (applicable to your design) is 20 mA but temperature dependent. I would design for 10 mA maximum.

The lesson: you can't take one datasheet parameter in isolation.