Have experimented this Oil question many times i have come to these conclusions.
I have to agree with CurryCanuk, you can make healthy Curries without Gallons of oil (i do), you just need to find out at what point does the Oil just become superfluous
1. You can make a dam fine curry without any Oil in the base Gravy.

2. It is possible to make a very close interpretation of a Bir Curry if you only add extra Oil in the second stage of cooking the actual curry.
3. you can use the Lighter color Olive Oil to make good curries as it has a much less overpowering flavor, as with traditional dark Olive Oil's.
4. You don't need to be strong with the Darkside of the Force to cook great Curries but it helps.

Close you're Eye's & open thy mind ;D
One thing, i think many are missunderstanding, you don't need to copy the Bir methods (for many of us this is imposable anyhow) to attain great results, is it not true that our goal is to end up with Curries that taste the same as an average BIr, i have posted on several occasions the attributes of cooking the final stage in the Oven which gives many of us without high powered Gas Burners the chance to get dam close to the results from a Bir.