1972 350SL - unleaded or Lead replacement

[mlc]

I have a 1972 350SL, the love of my life (after the current Mrs C of course). Can anybody provide a definative answer to whether it will run on lead free petrol. It runs perfectly on LRP but that costs 10% more and isn't always easy to get hold off.

Thanks in advance.
Mark

1972 350SL
plus a Mondeo for using in the real world.

 

[cowsurgeon]

Hi, long one this, here we go...
My 350SL is also the love of my life, but I dare say you have nicer wheels on yours with it being 8 years older...
Anyway, they've recently stopped selling LRP at my local garage, and I looked into this as a result.

It all depends upon the valve seats in your engine. If they are hardened then it should be no problem, although I know mine definitely aren't and mine's a 1980 model, so yours are unlikely to be. You can easily find out if your car can take unleaded by looking at the sticker on the inside of the filler cap door. It has tyre pressure details on but if it says "Super (auch belifrei)" unleaded should be ok

Otherwise you need an additive in your petrol to protect them. Originally it was lead, then lead replacement (not sure what they use - besides I think different fuel companies use different additives in their LRP's - that's why it's always best to choose a brand and stick to it). Now that LRP is being phased out you can either have your valve seats changed - big job - big money, or add an additive of your own.

I've heard different stories about this, a mechanic told me you can add a 'tablet' of additive to your tank, that lasts for x thousand miles, but I haven't been able to find one. Personally I add the stuff at the pump when filling up, sounds a faff but it only takes an extra 20 secs each time. Shell do an additive called 'Millenium' but I'm sure there are plenty of others - you can buy it in larger petrol stations. They recommend that you stick to the same one but they would wouldn't they? Oh, and they say that you can't keep switching between LRP and unleaded with an additive, not sure why.

Anyway that's everything I know about it, which all came from others anyway (big thank you to Malcolm Brown).

Chris

P.S. There's a website which says everything clearer than I did, damn.

http://www.shell.com/home/Framework...uels/qualityfuels/classic_cars_1008_1610.html

 

[mlc]

Thanks for the very comprehensive info, no mention of fuel on the back of the fuel cap so it looks as if it must need Lead replacement. This isnt a problem because both Sainsburys and Safeway sell it locally.
Not sure that I can agree with your your comment about the wheels, it has steel wheels with body coloured trims, I prefer alloys but try to maintain the car as original as possible.

thanks again.

 

[cowsurgeon]

How can you not like the matching wheels!?