Bosch Spark Plugs
 

Hello,
What is the difference, if any, between a H8 DC,
and a H8 DCO Bosch Super spark plug? My '91 190e
2.3 manual suggests the DCO, but some say the DC.
Thanks,
Randal

The "O" indicates a heavy duty electrode. I recomend the "O" series where ever available, regardless of what the original spec called for, so on an older model if it calls for a H8DC, I would recommend the H8DCO. If the "O" plug was not available I would feel fine using the original H8DC though.
Gilly

Gilly Same advice for an '87 190E 2.3?

Jeff

Yes, any time there is a Bosch plug available with the identical part number, but with an "O" at the end, use that one with the "O".

Gilly