The Nikasil problem
BMW used Nikasil, an aluminium, nickel, and silicon alloy, to line the cylinders of the M60 engines. The cross-hatched Nikasil linings react with the high sulfur content found in lower-quality gasoline, such as that used in parts of the United States. This reaction causes damage to the very top of the cylinder bore, where there is the most contact of the burning mixture and the cylinder lining. The damage prevents a good seal from forming between the piston and the cylinder wall, causing a loss of compression in the combustion chamber. This "leak down" will cause M60s with worn linings to exhibit a rough idle, and if the problem continues unchecked, the engine will not start.
The only permanent fix for this problem is the replacement of the short block with the equivalent block composed of Alusil, which do not exhibit this corrosion problem. After the problem was found, BMW issued an extended six-year, 100,000-mile (160,000 km) warranty to cover these engines at no cost to the owner.
The composition of the engine can be found by checking the serial number stamped into the engine block:
M60B30:
1 725 970 - Nikasil
1 741 212 - Nikasil
1 745 871 - Alusil
M60B40:
1 725 963 - Nikasil
1 742 998 - Nikasil
1 745 872 - Alusil
nevim teda jestli kvuli tomu budu zkoumat číslo motoru, budu rád když najdu dobrej kus a ještě tohle abych řešil
jenom sem o tom neslyšel, tak mi to přišlo zajímavý, ale jinak to neřešim..
Zajímavý je že nikdo nenapíše že fabia má motory nap**u 
a ti co byli na servisnim skoleni skodovky (vcetne me) uz vi ze jim nic takovyho do baraku nesmi 
´´ (neberte mě úplně vážně