Registered 2009 SLK200
Nuts bolts of course use grease etc but with modern spark plugs they say no grease or copper grease required !No manufacturer of either cars or bikes uses copper grease. Most motorcycle head bearings for example have the absolute bare minimum of lubrication from new. Its cost saving.
Every bolt that I remove, be it on the car or a motorcycle is copperslipped on re fitment, same goes for sparkplug threads. Just reduce torque setting by 10% as the copper grease lubricates on the way in.
It makes routine maintenance 50% easier the next time around. Use it very sparingly and you'll have no trouble. The other rule is if you remove a bolt that had locking compound (blue or green) then use the same type compound on re fitment.
But I'm sure I'm teaching some of you to suck eggs!
Its an old school req on old plugs from yester year with iron type plugs to have a smear of grease .
But modern day plugs for a number of years state no GREASE !
As can impact on torque settings etc etc .
Copper grease for modern day plugs dont req it it has to go in clean .
But im sure if Mercedes Benz dont use Grease on fitting plugs they must be wrong then .