Need for additive in lead free petrol for 1972 280SE 3.5?

[rutger kohler]

I have have just bought a very tidy 280SE 3.5 car. I was surprised when the owner told me it needed an additive added to the lead free petrol (gas) to protect the engine valve seats.  I have a 1969 280SL with an M130 engine and I have been told it has hardened valve seats and no need for additive so I am surprised a car 3 years newer doesn't have hardened valve seats albeit a M116?

[stickandrudderman]

No need for additive, just back the ignition timing off a little.

[rutger kohler]

Hi Stick, thanks for that.  Can you, or anyone else, recommend a decent tear down manual for this model car plse?  I have Haynes manuals for all my other cars, which have been adequate for my needs, but they don't seem to do one specifically for the W108 with an M116 engine.

[rutger kohler]

ps, I meant to say that the original owners handbook came with the car and in the back of it, believe it or not was not only the original data card, but the build card as well!

[andyburns]

Congrats.  Welcome to the club