Does anybody know where I can find datasheet of this 2*8 LCD
There are too many options for a 2x8 8-pins LCD. You will have to desolder it to see if there's a serial number or something. 

As for the interface: as far as I know I2C is the most popular serial protocol for character LCDs. 

I didn't expect a parallel interface as the most common one (HD44780) would need more than 8 pins. It normally has 11 lines (8 data, 3 for R/W, RS and E). In nibble mode it just uses 4 data lines, making the whole interface 7 pins. With the power pins and a pin for contrast that gives a total of 10 pins, 2 too much. 

Looking at the other answer however, they made a HD44780-like interface, leaving out the RW (so you can't read from the display) and the contrast (so you can't handle the contrast yourself, or there's a trimmer on the board), which gives 8 pins.