(adsbygoogle = window.adsbygoogle || []).push({}); For me I'd say about 400 hours, it was my first xbox 360 game so I played it a lot...
This was also over the course of a few years that I totaled it up.
I beat just about everything, had all stats maxed out, level 54 which is passed the limit because I was jailed and lost my main skill points a bunch o' times

So how long did you spend on oblivion?

Depends which platform Altogether, 400+

probably 100hrs or more, I have a friend(not really a friend he's a faggot) who put in like 100+ days.

hmm totally guessing as i can't remember, but probably around 300 hours. Far shorter than the time i've spent playing Morrowind (probably around 2000 hours)

i think it was a couple of hundred hours it was quality it was one of my first ps3 games before i had online

400/500 hours I'd say.
I still play it regularly, and I can safely say that is the only game I can play over and over again without ever getting bored.

Easily a year, collectively. Between the whole series more-so than just Oblivion, though.

On second thought, tone that down a bit. Maybe like 4,500 hours.

450+ easy. Great game.

Since I used to mod the game a lot I'd say around 1,5K-2K hours. And I still play it today.

I've fully played it through (All guilds / Main quest) 10 or so times and still have one profile I still use, so I'm sure it was well over 3-500 hours.