As EdBwoy said, PCV valve system check is first.
If all OK with that, I would switch to a dino oil, like 5w-30 for one oil change, and see if you burn less with that over the synthetic, (presuming you are burning the oil and not leaking it elsewhere)
On older engines that start to wear, the finer molecular structure of synthetic oils tend to flow more freely past worn components.
If the cause of the oil loss is from worn piston rings or glazed cylinder walls, using dino oil will help a bit, especially if you are using a synthetic oil lighter than a 5w-30.
I have had my m35x since new, never a drop of synthetic, it has 160k miles on it.
I would say I burn a quart of oil every 3k to 3.5k miles depending on driving conditions.