I have 161k miles on my 2013 Sonic LT, 1.8 engine, 5 speed manual transmission. Recently I noticed a puff of smoke coming out of the engine compartment coupled with slight smell of burnt oil. I cannot see any oil drips below the car when parked. I cannot see any oil leaks but i assume that a few drops of oil are leaking onto hot exhaust manifold while driving. Recently I have not seen any more smoke and no oil leaks either. Is it a good idea to replace the oil cooler at this stage along with associated piping and seals? The cooler probably deteriorates with age and miles and I would like to avoid a catastrophic failure as it may lead to engine damage. Is it necessary to remove the exhaust manifold to replace the oil cooler? Even removing the manifold sheet metal cover is not that easy as you must pull out the dipstick tube and remove the oxiygen sensor.