I have a 00 Corolla, VVTI. I brought it to the garage a while back to ask them to check it as the oil was being used very quickly. They told me that there was a very small leak in the oil tank, but that it wasn't worth fixing, I should keep an eye on it and top it up as required.
But it seems from the above that its actually more likely that its burning oil????
No such thing as an oil tank. It's a sump.
Park on clean concrete for a few weeks. If theres no stain underneath it's burning oil.