Some oil in cars go like this as they may not be getting to the correct oil working temp
did you put the correct oil in you car ,do you use it for short runs only ?
Get an oil flush done and make sure you have the correct oil for you car ,also make sure you have the correct thermostat in you car and it may be on a summer stat and you engine might not be getting hot enougth for the oil to work effectivly .
Short runs are not good for big engined cars as they dont get up to working temp
also make sure all breather pipes are clear
Get a garage to do a test on your coolant and they can tell you if you head gasket has gone ,this only takes a few mins
Dave
December 2008