My brother in law is a mechanic. I've rebuilt engines and restored a couple vehicles, myself, as well. Big deal. I am also one of those anal people who samples their oil and sends it out for analysis. In my daily driver (Acura MDX) I change when the OLM indicates to change, as I don't want any warranty concerns. Last time that was at around 7,900 miles (IIRC). The analysis came back impeccable and the TBN was still great. The lab even encouraged longer drain intervals -- although I will continue to follow the OLM on this vehicle until the warranty is up.
A 10k OCI is perfectly reasonable for most
* vehicles when using a quality filter and full synthetic oil designed for extended drain intervals.
*Most vehicles means
most vehicles. There are some vehicles that should NOT use extended drain intervals. These include air/oil cooled engines (VW, some motorcycles) or engines that are known to have a predisposition to sludge. The VW/Audi 1.8T comes to mind, as does some years of engines in the Toyota Camry.
The manual for the QX30 specifies you MUST use oil that meets the MB229.5 specification. Mobil-1 FS 0W40 is an example oil that is certified to meet the specification. That oil, coupled with a quality oil filter -- such as the Mann HU7116Z -- will last a 10k mile OCI without any problems.
If you use a crappy filter, or oil not designed for extended drain intervals, then you may have problems...
The "cheap insurance" argument is silly. I could talk about how it would be "cheaper" to use quality oil and follow the manufacturers maintenance schedule. I could also point out that wear increases after a fresh oil change, then levels out for the usable life of the oil, until eventually wear increases, again; changing your oil too often will keep you in the initial wear-in period more of the time. But instead of having those arguments, I'll just do this:
I bet you cannot show an example of an engine failure that meets these criteria:
- Always used a quality, name-brand engine oil. From sealed containers. Purchased from a reputable retailer. Not excessively old stock.
- Always used a viscosity appropriate for the application.
- Always used a quality filter, rated for the OCI.
- Always met all vehicle manufacturer requirements for parts/service.
- Oil and filter were changed per manufacturers specification.
- Experienced a failure that is directly attributable to oil age (sludge, additive depletion, something similar)
- Engine is not among those known to have a predisposition to sludge*