My US Bosch catalog shows the H8DC for the 16V, but the Euro version may have specified a colder plug. (The lower the number the colder the plug.) The gaps for all this series of plugs for use on MB engines is usually listed as .032".

Given typical US driving conditions, the hotter H9DC that is specified for most M103 engines is probably okay for a 16V unless you drive the car very hard.

The OE plugs for model years beginning in 1988 for M102/103 engines had an "O" suffix (such as H9DCO) and this suffix indicated a larger center and ground electode, which theoretically improved plug life. These are perfectly acceptable for all model years if you can find them, and they were usually only available at dealers.

My experience with the H9DC on the M103 engine is that they have little wear at the recommended 30K mile replacement interval and will probably easily run 60K miles on a car that doesn't develop a fuel mixture problem or have excessive oil consumption.

In any event, it's important to use a non-resistor plug to avoid rough idle issues and possibly emission test issues.

Duke