What is the “Nikasil issue”?
The “Nikasil issue” is a serious problem that affects all BMW motor cars with engine blocks with “Nikasil” liners in their alloy block when high sulphur fuel has been used. This is 8-cylinder models with the M60 engine made from approximately 1993 to 1996, and 6-cylinder models with the M52 engine made between 1995 and 1998 (note M52 Nikasil engine never went to the USA). The “Nikasil issue” is extremely serious as the final result is a non-functioning engine. The material “Nikasil” is also known as “Galnikal”. "Nikasil" is a very hard dispersion layer of galvanically (electrolytically) applied Nickel applied to the soft alloy bores to prevent wear. If this hard layer is damaged, excessive bore wear occurs rapidly.
What causes the “Nikasil issue”?
In short, high sulphur fuel. Contrary to popular belief, the “Nikasil issue” does not only affect the USA. It is potentially in existence in all countries, but is a particular problem in the UK and the US. It would appear that Nikasil-lined blocks were not tested with fuels that had a high sulphur content, which was unfortunate because the chemical reaction between the sulphur in the fuel and the nickel lining in the block which damaged the hard nickel lining. Once the lining is damaged, excessive bore wear of the soft underlying alloy occurs very quickly. Some Nikasil engines have failed in as little as 30,000 miles.
Fuel high in sulphur was imported into the UK and (apparently in very small amounts only) into continental Europe. The problems occurred first with cheap (supermarket) fuel in the north west of the UK, although in time the whole of the UK was affected - and it was no longer just supermarket petrol that was causing problems. Having said which a vehicle run only on good quality fuel which was low in sulphur would not have problems, but there was no way the consumer could know which fuel to buy. There do appear to be quite a few Nikasil-engined vehicles which, either through luck in the fuel used or some other mysterious reason, appear to be absolutely fine even after very large mileages.
Continental Europe (through essentially not getting high sulphur fuel) appears to be largely unaffected by the Nikasil problem: it would appear that they did not suffer from imports of high sulphur fuel. I have not heard of any problems with Nikasil cars on the Continent, nor have I found any reference to any difficulties.