How long would a typical gasoline engine last in terms of milage if all maintance was followed?The engine would be your average gasoline engine.No after market items.Regular conventional oil was used and either 3,000-6,000 mile OCI.No towing.Transmission was serviced when needed.Some stop and go driving and mostly highway.i hear people are keeping their cars/trucks longer and some are using regular products on their rides.Thanks Joe