So you drained 500ml of oil from your intercooler!
How many km was that from? Did the engine use any oil between changes?
If it's relatively easy to remove it would be worth cleaning the intercooler out with some solvent like methylated spirit.
Where did you get the larger intercooler, did it make a difference and was it an easy fit?
The core on mine is about 300 x 200 x 50mm so your 600 x 300 x 100 is 6 x the volume!!!!!!! 3 x the frontal area and double the thickness. As they say, think of it as a heat sink reservoir with the ability to absorb heat rather than dissapate it and it shows the instant advantage it has.
Thanks for the tips.