The Denso T20EP-U is actually one heat range colder than the H9DC(O). A T16EP-U would be closer, but there's no such animal... only a T16EPR-U, which is a resistor type.

NGK heat range 5 is the closest match to Bosch 9, so the best NGK to use is the BP5EFS, but some have reported they are no longer available.

I definitely would not use colder than OE plugs on a car with high oil consumption.

Duke