Here is info I found regarding the V8 and V12 issues ...

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Hi Jeff;

Welcome to the 8 Series forum. Requests like yours are very common on this board due to the resurgent popularity of the 8 Series.

The archives are rich in information for you to peruse. Answers to your questions are contained in the archives.

For the moment, since you're a newbie, here are direct answers to your questions:

1) I have heard that some of the 4.0 liter 8 cylinder engines had problems during some years. Are there any known problem years for the 840CI?
Answer: Yes there were Nikasil block engine issues for 1994-95 540's, 740's, and 840's (plus another 5 series model I've gone blank on). When using the search engine below, enter "Nikasil" and you will find a wealth of information about the problem and resolutions. Some owners of 1994-95 840Ci's have reported no problems with their engines, while others in "high-sulfur" content gasoline states report lots of problems.

2) What was the difference between the CI and CSI models?
Answer: The 850Ci was the base V12 8 Series. The 850CSi was the ///M derived version. For specific differences, visit this website for details: E31.Net Website

3) Are there any benefits or problem issues with the 5.0 liter 12 cylinder engine?
Answer: Benefits are numerous. Torque. Smoothness. On and on. Problems/Issues: if the 850 V12 has not been properly maintained, it will cost you dearly to bring it up to standards. When looking at any 8 Series for that matter....always ask for service records...if none exist, be wary. Any car that hasn't been maintained ultimately will catch up with you.

Good luck on your pursuit.

Jud Spencer
E31 Registry Agent

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1992 500E (Daily Driver)
2004 Porsche RUF 955 Dakara 550