Mercedes-Benz Forum banner

1 - 4 of 4 Posts

·
Registered
280SL 1982
Joined
·
18 Posts
Discussion Starter #1
I have just bought a 1981 280SL, so am a new boy to the forum. Where can I get some answers to whether it will run on unleaded. The previous owner used LRP and did very few miles, but LRP is soon to disappear from the UK, so what then. It seems that after 1985 there is no problem and before 1975 unleaded is a definate no, but what in between.
One source said that all aluminuim head engines have hardened valve seats so the question does not arrise, but any help from the forum would be gratefully received.
 

·
Always Remembered RIP
Joined
·
520 Posts
Personally I would stay clear from LRP as there's no specific guild lines as to what the f...

Personally I would stay clear from LRP as there's no specific guild lines as to what the fuel companies actually put in it.
4 star petrol is still available although slightly more expensive. I'm presently paying 98p per litre for fuel in my 220SEb but I feel because of the low mileage I cover it's worth the extra piece of mind.
If you use a far bit of fuel than an additive may be your best bet. I know of quite a few people who use Castrol Valvemaster with no ill effects and it's available from any Halfords at around £5 a bottle or Valvemaster Plus (contains octane booster) costs a few pounds more. Redline is also highly recommended in the classic car community although harder to come by. But if you choose an additive stick to that particular one as some of the active ingrediants don't mix very well.
But then again a good specialist will probably charge less than a £1000 to replace the valves with hardened ones and the valves in now will have enough build up to cushion the blow for a good few years.

http://website.lineone.net/~angela-iwnet/triumph/fueladvice.htm

http://www.jec.org.uk/4star/index.htm

http://www.castrolclassicoils.co.uk/valvem_new.htm

http://www.redlineoil.co.uk/page01.html
 

·
Registered
280SL 1982
Joined
·
18 Posts
Discussion Starter #3
The old unleaded question.

Thanks for the advice, I think I will just use Shell Optimax and see what happens. Do you know if the point about aluminium cylinder heads is true? It would seem to make sense; as the metal would not be hard enough to produce a valve seat without help. Unlike cast iron which could be used without an insert. This is, I understand, why the old BMC 'A' series engine, with iron heads, suffers so badly when run on unleaded, and why it was selected as the test unit for the over the counter additives tests.
 

·
Always Remembered RIP
Joined
·
520 Posts
Not sure about the aluminium cylinder heads being lead free or not. Why not phone the M...

Not sure about the aluminium cylinder heads being lead free or not. Why not phone the MB technical centre in Milton Keynes on 01918 245451 , they're always very helpful.
You could also pop the rocker covers of, set the valves up and then measure the gaps again say every 5,000 miles. This will give you an indication to whether the exhaust valve seats are wearing down.
I'm seriously considering just using unleaded in my SEb simply because as the lead build up is supposedly good for over 50,000 miles paying an extra pound per gallon for 4-star means I'll spend around £2,500 before I reach 50,000.
 
1 - 4 of 4 Posts
Top