yeah i agree with the service every 5000k's
... and k's is ultimately not a very accurate measurement.. two cars that have done 50,000k's, can be VERY different in condition.. eg. a skyline with an 18 year old driver, still learning to drive a turbo car is going to be FAR worse condition than a 50 y/o skyline enthusiast who takes care of the car from the time it leaves the dealership!
at the end of the day, the only reason you buy a car with less k's is for resale value (unless of course you are one of these low forms of human beings that actually winds odo's back!!). You buy a car mainly on it's condition, not it's km's