Like i mentioned I know that in aviation these things are very clear and easy to find
I an not sure what you are saying there. I doubt if Pratt and Whitney shares its design criteria for engine components with GE or Rolls Royce. As a whole when the engine is completed it has to go through certification for air worthiness. In an airplane, if a part fails, the airplane cannot just pull over to the side of the road and wait for a towtruck to arrive, so parts are designed to be fail safe and operable until the next engine overhaul will occur. Airplanes do not have such a thing as a warranty.
Bolts from a bin for an aircraft engine are selected so that all bolts meet a minimum criteria - anything above is OK, anything less than is not. ( Thus you have higher military specifications, aviation specifications etc for parts and material selection than general )
Buy the way, I believe that car manufactures invest time and money in calculating when is an appropriate time for a part to fail. I mean the spare parts market is huge and if they built fail free cars and parts it would cost many people there jobs and others would just lose tons of money.
For a car, as a whole it must meet certain safety considerations on the road, such as brakes never failing, handling, etc. A non-life threatening component could be designed for a 1 to 2 year life such as wiper blades, or a 5 year life such as belts (maybe ). The powertrain ie engine, transmission, axles - is now probably "overdesigned" beyond the life of the car for obviious reasons. Other components on the engine might have an maximum expected life ( to last at least a certain number of years or cycles ) So thus you have the warranty thing to take into account when designing your water pump, but obiously there is not a one to one relationship of course - the pump just doesn't fail the day after warranty expiration.
You could design your water pump to have an expected life of 25 years if a seal can last that long, but what would be the point in that if the car is going to be scrapped after 10 years. A $500 water pump would just add to the initial price of the car and for very few people this would be important buying/selling feature.
for the bolt example - the bolts are selected so that an average, or 80% on a bell curve, or a certain number of standard deviation of the bolts meet design criteria so the selection is more relaxed.
I hope that explains it some more for you.