I have used it for 5K kms... added to a fresh mineral 5w 30 Mobil on a V6 GM with hyd. lifters.
I'm using the same car for 5 years so I'm used to how the engine's sounds get different as the oil deteriorates. I can't say CD2 lenghten the oil's performance, but improved it during the use. (Please note that this is a personal observation without test data.)
Anyway, this stuff did not made the oil proggressively darker perceptibly as I was expecting, but it might be because of that the engine was already clean since I change oil often. Mobil -mineral, gets slightly darker after 5ooo kms, it was the same progress with CD2 during 5oookms.
Ticking noises almost gone at the idle, and engine was perceptibly more smooth/silent past 65mph (100kph) speeds. I can say it pushed the usual sound levels of the engine at specific speeds -that I got used to- at least 30kph farther.
I kept this oil-CD2 combo ~1ooo kms longer than usual, after changing it every sound came back w/o the CD2 in the sump again. On the bottle it advises: "Use at least every 2,000 miles". So, could this really be a cleaner?
I think it's main benefit might not be the cleaning eventough advertised as it (but may be the detergency). It is not thick, very liquid. Made this engine perceptibly more smooth at higher revs. and more silent at the all times. I didn't experience any oil use (and I wasn't need to add between changes.)
One of my friends (who advised me CD2) experienced the same things on a 1.6lt 4cyl European Ford.
BTW. CD2 also gives the moneyback satisfaction guarantee.