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Join Date: Oct 2009
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There is no conflicting information at all regarding the correct spark plug for the M88/3 engine:
It uses the Bosch X5DC plug.........end of story.
For those who like to use an NGK plug, the D7EA will be the closest equivalent, but I do not recommend using this plug in the M88 engine, as it has a slightly different hex configuration to the Bosch item, with the result that the BMW-supplied plug wrench will not engage it properly during installation/removal.
So just stick with the Bosch plug and you can't go wrong.
1987 E28 M5 (DC98) Delphin-metallic/Midsilver Nappa
1986 E23 745i/M88 (6928) Arctic-metallic/Oyster Nappa