i know 2 people that have had to have new engines fitted to there focus , the 1.6 is the weakest out of the 3 engines . the problems are with the bottom ends not sure what but ford said that her engine was really mashed up , they said she had put the wrong oil in , so she had to have the oil tested to prove to ford that all was well at her end and lucky ford did all the work under warranty. she later found out that it a common fault and thats why all secondhand 1.6 engines sell for around £450/500 and you can pick up a 2.0 engine for £200

cheers paul