Long oil service intervals are JOKE! (applies to diesel engines)
Cheap garage oils last about 5000km. I’ve recently received a report from my new car – results were shocking. It’s a car from Germany with full service history. Oil had just 10k km and it was, simply put, killing the engine. Few such oil services and engine is dead!
Premium oils last about 10,000km. As mentioned above by, my usual oil replacement interval was max. 10k km.
Oil is cheap – engine NOT. Filters are cheap – car NOT.
Soot is a problem number one for diesel engine oils – despite oil still has additives and keeps viscosity, it’s full of soot at about 10k km!
VAG cars are especially sensitive for clean oils – unless you wish to kill your turbo.
You never know with oils – marketing is based on lies. I suggest you to invest in oil analysis – it’s cheaper than car engine replacement!