About 35 (thats miles, not thousands of miles!).....or it was in the case of one that was bought on a farm I did a bit on back in the day. Bought brand new in 98 or 99 , it did not make it back from the dealers to the farm before it threw a rod straight through the side of the block and stopped very suddenly!!
Needless to say a new engine was fitted in double quick time by the appologetic supplying dealer! Upon investigation two oilways had not been drilled right the way through....amazing it lasted as long as it did really!!