Much has been said and written about the superiority of the gear-driven oil pump/balance shaft design, and as an engineer I am among the first to recognize this. However... many well- and properly-maintained engines with the chain-driven system have gone well into the 300,000 mile range without any catastrophic failure. So I have the following question: absent any signs of imminent failure of the oil pump unit and with all else being as it should be in the engine, and with no undue visible wear on the sprockets, would it not be to an ownerâ€™s financial advantage to replace just the chain and tensioner at the time of a timing belt/water pump, etc. change? Especially if this is just the first timing belt change? Any comments and/or observations would be welcome.