The Nikasil Issue
For potential buyers of BMWs of the mid to late-90's an understanding of the potential problem is absolutely crucial.
'Nikasil' was a material used to line the bores of alloy cylinder blocks of certain engines. Specifically, these are the engines designated M52 and M60 by BMW's engine coding system.
In short, the problem was/is that premature bore wear can occur when engines fitted with these liners were/are run on fuel containing high levels of sulphur. This problem became fairly quickly manifest in the USA, U.K and certain other markets
around the globe where sulphur contents were high especially prior the introduction of Ultra Low Sulphur (ULS) fuels in the U.K.
It would appear that the problem did not occur in other markets such as mainland Europe where ULS was already the norm.
The symptoms of excessive bore wear may manifest as the following: poor/rough idle, excessive oil consumption, loss of power and ultimately in severe cases a failure of the engine to even start!
Whilst BMW were not the only manufacturer to use Nikasil it is safe to say it cost them a great deal of money in replacement engine blocks under warranty and under 'goodwill gestures'. It is however
important to be aware that not all 'replacement blocks' were of the 'Alusil' type (ie. not afflicted by excessive bore wear). Initially, some blocks were merely replaced with a further Nikasil block! You have been warned and you need to check even when there is
documentary evidence of the statement'New BMW engine fitted at XXXXX miles under warranty'!!!
In simple terms, the afflicted V8's are the earlier 'M60'engine equipped cars eg. 4.0 litre engine. The later 4.4 litre V8 'M62' engine was 'Alusil' lined (for certain markets...see later!) and hence does not have the 'Nikasil' cloud hanging over it.
I say "certain markets" because BMW did continue to use 'Nikasil'even in the M62 except for certain countries...examples of the exceptions being the USA, Mexico, South Africa and (reassuringly) the U.K!
For further information on the 'Nikasil Issue' the following article is clear, well-written, comprehensive and will answer most questions with links to further articles:
The BMW Nikasil issue by Lestac Ltd
and from Bimmernut.org