In your waterboxer-equipped Vanagon, there are two marks on the dipstick—between which is considered “normal” oil level. As noted in our break-in guidelines, the amount of oil required to go from the lower mark to the upper mark is less than ½ quart. The most common reason these engines burn too much oil is due to over-filling. You would be surprised how often it happens.
So, when you are trying to get an accurate reading of oil consumption, you should keep the oil level as close to the lower mark as possible during your test. That is, don’t add any oil until the level drops below the lower mark. Then, add oil until it is back up to the lower mark, but not above.
In order to get an accurate measurement of oil consumption, you need to do this over a 1000-2000 mile period. Check your oil at every fill-up, and note where it is. Always check your levels at the same temperature. This is very important: The level changes quite a bit with temperature; thus the range on the dipstick that is considered “normal." So, if you have been checking your oil level at fill-ups, then decide to check it stone cold the next morning—you will find a difference that has nothing to do with oil consumption!