1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

[Nial]

Since Lead Replacement Petrol (LRP) is being phased out here in Australia in the next year I was wondering if my 1976 Mercury 850 will run ok on unleaded petrol. I have the original manual and it's says it will run on leaded, low-lead and lead-free petrol/gasoline as long as it has a minimum octane rating of 87. All the regular unleaded has a rating of 91 and you can get other that are 95 and 97. Any advice on which fuel i should use and which will run the best would be great. Thanks.<br />Nial

 

[JB]

Re: 1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

Hi, Nial.<br /><br />Your Merc will run better on unleaded than with the LRP.<br /><br />The "minimum octane rating" quoted in the manual is by the US system. Your system would rate that petrol at 91 octane.<br /><br />Conclusion: Your unleaded regular (91 octane) is better for your engine than the LRP.<br /><br />No worries.

 

[jimmbo]

Re: 1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

Don't worry about it, these engines never needed lead or the lead substitute in the first place. As you stated the owners manual says you can use lead free gas if it has a minimum octane of 87.

 

[Clams Canino]

Re: 1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

Yep.......... lead was never an issue. Octane rating is all you need.<br /><br /><br />-W

 

[carrotsnapper]

Re: 1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

Does this apply only to marine engines? I had a 78 Ford PU that ran on leaded gas. I had heard that eventually the unleaded products would ruin the motor. I don't know how. I'm not a motor guy. My brother wants to buy a 76 Ford to pull his boat and I told him it was an issue to be aware of. I was just wondering.

 

[JB]

Re: 1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

Waaay off topic Carrotsnapper.<br /><br />In addition to it's other features, tetraethyl lead lubricated valve stems.<br /><br />The worst unleaded can do to pre-70 engines is increase wear on valve stems and guides.<br /><br />I suspect that the '76 and '78 Fords had engines suitable for unleaded fuel.

 

[jimmbo]

Re: 1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

I know GM started, back in 1971 designing their engines to run on nolead

 

[carrotsnapper]

Re: 1976 Merc Changing Fuel from Lead Replacement Petrol to Unlead Petrol

Originally posted by JB:<br /> Waaay off topic Carrotsnapper.

Sorry JB, It just got me a thinkin and that don't happen too often.