As for Saturn, those cars loose value incredibly fast, even though they were discontinued. So I also agree about getting rid of it while it can still be sold or traded for some value.
Hi that is because there is no oil in the bearings this does indicate the wear in an engine as oil drains from bearing surfaces when wear is present in such quanties.
the wear in an engine happens accept it. that is why we need to keep things serviced regularly. some additives are added to help preserve the engines life sometimes it works. products like STP and wynnes help it last a bit longer when added to he oil.
Petroleum based oils will not do as well when it's cold because of their viscosity from paraffin that's part of it. Use a synthetic engine lube and even use a superior gasoline additive. I use a product called "Performance Improver", or P.I. as it's known by.
It is a knock or a ping? If it is a ping, one of the lifters may be loosing oil while it sits. I am not sure what it would be if it is a knock that quits when the engine warms up.
It could be piston slap or bearing wear. I would trade it in. Make sure the engine is hot when you take it to a dealer.
You could use a slightly thinner oil in winter.
