Leaded/Unleaded

[IXLR8]

Well, I'm sure that this question has been asked and answered a million times, but I couldn't find it in a topic search.

Does an early (64,65) 230 SL require leaded gas? Does unleaded gas damage the heads/valve seats?

Thanks in advance for your reply.

[TheEngineer]

Unleaded is preferable! I had a 220Sb four door sedan and had problems with the plugs fouling with lead. Like a little string bridging the electrodes. I Germany they had BV-Aral, which is an unleaded fuel and these engines were designed for that. You will also find that your car runs well on regular unleaded with the timing set to factory specs. One advantage of fuel injection is that the fuel is injected in front of the intake valve. That cools the intake valve. After you run for a while on your favorite brand of fuel, look at the color of the plugs. It is the best way to judge what's happening inside your engine.

[Jonny B]

My understanding is that the MB engines had the hardened valve seats that did not require the cooling/lubrication of leaded fuels. I have an early 250SL and I use either BP or Shell premium fuel. No issues after 5+ years.

[Ziggy]

Can you still get leaded fuel in the US? MB states it would be better, but you can only get unleaded nowadays in Europe... you just have to check the valve clearances more often. Do not use any lead substitute products however, this can damage seals and such in your injection pump. Yes they had 'hardened' valve seats at the time, but these are nowhere the quality of todays hardened valve seats.

[Paddy_Crow]

I wouldn't worry too much about the hardness of your valve seats, it's really cast iron heads with non heat treated parent metal seats that have an issue with wear.

[mdsalemi]

Not only can't you get any leaded gasoline here in the USA, at least in the midwest you can't get pure gasoline, either.  Conventional (save for the few stations that sell racing fuel) pump gas--even the touted BP-Amoco--is ALL E10 now.  That's 10% ethanol.  No choice.

That's from my friend at Spencer Oil Company in Roseville, MI.