What caused this lower engine oil leak on a 2000 V70?

[abscate]

Use the dipstick and check your oil on every other tank of gas. Don't let the oil get below the hash mark on the dipstick

The oil light reflects pressure at idle, you can have as little as a liter of oil in your motor and still not have the light. Meanwhile, your Pistons and cylinders are ruined.

1 liter per 1500 miles isn't hugely excessive consumption.

[FireFox31]

I wonder if the leak got significantly worse after I had my timing belt changed. In May, I found out that my cylinder 5 was burning oil because the spark plug destroyed itself. It just so happened that I was due for a timing belt, so I had my dealership, who I trust highly, change it. Maybe the dealership roughed up the balancer and its 17-year-old seals when removing it for the belt change.

But I'll swear the oil stains have been on the underside of my engine for years. I'll have to go back and look through my notes and pictures.

[erikv11]

Silly if they removed the balancer just for a timing belt job, but who knows they might have. Anyway that wouldn't bugger up the seal unless they ruined the crank! Whatever leak you have sounds very slow which is good news, but maybe check it sooner than 700 miles just to be sure. You don't want to wait until it is wet all over the passenger side again.

The ticking will come especially at startup, from the lifters on the top of the head, but can be bad always if the seals get bad enough.