I agree with you in this respect but highly disagree of prolonging oil change till 7000, 8000 or 10000 kms. I agree that these special oils can be prolonged even to 20000 kms and so on. In europe and middle east it is and that is only possible prior to fuel being pure. A contaminated / adulterated gasoline fuel lets say RON92 with high MMT along with mixing of Kerosine and other illegal not recommended blending additives induces high level of carbon, ash & other impurities than normal during the combustion process which got mixed with the lube oil reducing its life and due to this reason i prefer to change oil filter at every oil change despite whatever OEM says and despite a gud brand of lube oil not to be prolonged above 5k kms in our region specifically.
I personally felt in my previous cars that the engine sounds starting rough after crossing 3500 km of oil change.
and yes despite usage of lube oil as per recommendation from some where else other than dealership if you have good relations with the dealership then warranty shouldn't be an issue.
