This issue about warranty really needs to be clarified and understood.
Warranties are mandated by government, however the length of time is arbitrary. Warranties are intended to protect consumers. They are to cover components that fail due to faulty material, design, or workmanship including the labour to re and re the component. The manufacturer is obliged to cover the warranty provided that the consumer does not abuse the vehicle or component that failed, and that if any maintenance has been prescribed to maintain the integrity of the component it must be performed. Each individual part of the automobile is warranteed for a period of 1 year and specific parts warrenteed longer. General mainenance is not required to maintain a warranty of a specific part - only the maintenance that is required for that part. Also, suggested warranty procedures by dealerships have nothing to do with maintaining warranties. Only official written documents by the manufacturer apply.
Dealerships do not need to perform maintenance to keep the warranties intact. Anyone can perform that service. Also, for many components, the so called A and B service does not even have to be performed. For instance, if the top delaminates within the warranty period, then even if no service had been done on the vehicle the warranty on that part must be honoured, oil changes have nothing to do with electronic failures, a faulty gearbox is not related to changing engine oil or filter etc etc.
There is no such thing as keeping "a" warranty valid. The car is covered by separate warrantees on separate parts. If the engine develops an oil burning situation, then that may or may not be related to not changing oil, or other abusive behaviour of the owner and in that case the warranty on the part that is faulty in the engine part would be invalid. This however has nothing to do with any part that is unrelated to changing oil and filter.
Dealerships love to pressure owners to return to them for service and threaten loss of "warranty" if their service is not done. They really need to be confronted with the logic of these threats. Ignorance of consumers allows them to get away with this tactic. They put the onus of warrantees on the heads of owners whereas it is actually a mandated function for manufacturers. More profit is made from service than from sales.