Quote:
Originally Posted by The HACK
I wouldn't do that, simply because oil on spark plug threads usually indicate to me (and any competent mechanic) that there's a leak somewhere in the valve cover gasket.
Plus any lubricant on the thread is going to throw your torque spec off. Not by much, as much as 10%, but newer spark plugs are VERY sensitive to torque spec and angle of torque too. Not the S54, but we changed out the spark plug on my buddy's F30 328i and chased a mis-fire all week. Turns out the plugs need to use a swivel socket due to the direct injection hardware requiring the spark plug be installed at an odd angle, and torqued to a very narrow range of twist higher than what's specified on the plug from the manufacturer. When we removed the plugs, 3 out of 4 plugs had the ceramic insulator cracked.
The S54, on the other hand, is much more straight forward. No DI hardware means the plug and the socket is installed just like how it always has been done in the last 20 or so years, and because no swivel socket is used, it's not as susceptible to small variations on torque spec.
Normally, I put a small dab of COPPER anti-seize on the spark plug to make the NEXT spark plug change easier, and torque it to the low end of the torque spec. But the MZ4 Coupe, being driven only on weekends, I haven't had to do any of that yet.
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Fair point. But nobody else touches my car except me. I don't douse the thing in oil, I just add a tiny amount to the threads. Also maybe I'm crazy but I don't use a torque wrench on the plugs. I use my calibrated hand to tighten it to "just enough". No issues after 9th year on two S54 engines.