as most of the other guys have said regular oil
and filter changes it also helps to give the engine
a flush with diesel , when doing an oil change just
drain half the oil out then a about 2 litres of diesel
into your engine and run it for about 15 minutes
before changing old oil and filter
that will keep all the breathers clear and your engine
sweet and you should use mobil 1 oil its quite expensive
@ £35 for 4 litres but is the best oil for the job
hope this helps mate