Lead or no Lead, that is the question...

[patnorth]

Hi everyone,

maybe someone of you has the answer:

I recently purchased a beautiful W112 300SE swb "fintail", the engine runs nice and smooth (especially when warm) and I am currently giving her a smooth restoration - improving bits and pieces but leaving most of the original interior patina.

my question is: regarding the valve seats - would they need to be reinforced or are the W112s known to digest the modern unleaded fuel without causing longterm damage?

and as I have your attention - has anyone any experience with this new eco fuel and the use of it in classic cars, some say that due to corrosion the fuel tank, pump, pipes and injector pump have to be changed or recoditioned.

thanks for any info

Patrick

 

[jefrs]

I ran a lead-only Volvo 245 for many years by adding Castrol Valvemaster Plus to ordinary unleaded fuel. I did not notice any problems, indeed I got over 330k and would have got more if it had not been hit (whilst stationary) by a very large truck. Corrosion was not a problem but I did have to replace the main carburettor jet and had a few problems with cheap fuel filters and float bowl sediments, but do see mileage.

Btw the modern fuels are not ecologically sound, because the lead has just been replaced with the even worse molybdenum. Painting the pump green does not make it environmentally friendly.

 

[Olivier]

was not the lead just add to the fuel but was never there? Creating a lot of toxic waste from the gases?

 

[jaymanek]

I suspect your head will be fine on unleaded, I found out that even my 69 pagoda had hard seats from factory and are fine to run on unleaded.

However a bottle of millers in every tank can't do any harm

 

[patnorth]

thanks for the infos.
I agree, even though the head and engine are full aluminium I do not want to risk it and add valve protection.

any opinions on octane - 95 or 98, the 6 cylinders are said to be fine even with 91 octane???

re biofuel - what I am referring to is the new E10 fuel with bioethanol added to it, rumours say that the ethanol has somewhat agressive properties in terms of oxidation, I know this is relatively new but eventually all petrol driven cars will have to deal with it. Any info?

greets,

Patrick

p.s.jaymanek - impressive collection!

 

[jefrs]

Castrol Valvemaster is far more economical than Millers, you use a small metered amount, not an entire bottle. The Volvo 245 did not have hardened seats.

The lead was added as an anti-knock agent: lead-octane. It prevents detonation of the fuel/air under compression. Lead-free does not have "octane" but it is an equivalent number. The higher the number the less the risk of detonation (and shortened con-rods or toroidal pistons), and a higher compression ratio can be used. Generally a high octane burns more smoothly over the rev range, less flat spots. I preferred then and now to use 98 because better bottom and mid-range pick-up: better fuel mileage too.

If you engine senses the octane then it may advance the timing. Back when, we would deliberately advance the timing to improve performance when using high octane. If you use third world fuel then you muse retard it.

As I alluded before the soft-valved Volvo 245 did over 335,000 miles, about half of that on lead-replacement additive Castrol Valvemaster Plus into high octane lead-free petrol. And there was still a lot more life in the engine.

 

[patnorth]

I take it, Castrol valvemaster is the stuff for long life! thanks for the infos.

I have followed the discussions on german forums, there seems to be quite some concern about the E5 and E10 fuels, set aside that consumption tends to rise by about 3% which is concidered to be neglible, but the oxidation effects would be regarded serious.

 

[vijilants]

In addition to this forum, I would also recommend that you join the official mercedes benz owners club...The Mercedes-Benz Club

They have a lot of good advice and info on the older classic models such as yours

 

[Stratman]

As well as having anti knock properties the tetraethyl lead was found to have a lubricating and cushioning effect. This affected the design of valve seats and stem seals, which took into account these properties.

When Shell decided to experiment with selling unleaded fuel without telling anybody they came a big cropper with Vauxhalls in particular and had to shell out (see what I did there?) for a lot of broken engines.

The white deposit in the tailpipes of yesteryear was the lead in the exhaust. A badly adjusted mixture would cover it with soot, but a car running properly or even on the weak side always had the telltale white pipe.

 

[patnorth]

yep, white is quite right, on the kontinent and in scandinavia the coloring could also be light to darkish brown

 

[jefrs]

I take it, Castrol valvemaster is the stuff for long life! thanks for the infos.

I have followed the discussions on german forums, there seems to be quite some concern about the E5 and E10 fuels, set aside that consumption tends to rise by about 3% which is concidered to be neglible, but the oxidation effects would be regarded serious.

I noticed the Volvo 245 got improved consumption* over the old leaded fuel when using Shell Ultra with Valvemaster Plus (Ultra has just increased to 99 "octane"). Perhaps my "octane rating was a bit OTT but could not always guarantee getting the super grade fuel so carried the more expensive Plus version. There was a noticeable improvement over ordinary unleaded which was less efficient and less smooth i.e. might flat-spot.

I also put triple electrode spark plugs into it which gave improved low to mid-range pickup, much smoother, thus improving consumption too.

* I never measured it but guess +3% improvement - say from 22-26mpg to 24-30mpg

 

[mandrak]

I agree with jaymanek that unleaded fuel won't harm the engine.
Many cars run on LPG which is, of course, unleaded and even has the lower octane number than petrol.

 

[219]

I ran my Ponton for years on unleaded without any additives - never seemed to do any harm .

I know of quite a few others with similar cars who did the same .

 

[jefrs]

Regarding it damaging the engine - it's down to the valves and seats.
The lead-octane also acted as a lubricant.
If you have "hardened" valves/seats then unleaded is ok. However the 86 Volvo 245 had "soft" ones and Volvo said "not-ok, use leaded or lead-replacement". Ancient engine design. And I got many, many miles out of it like that.
If in doubt, ask the manufacturer.