WHEN I bought my Honda Civic in 1985 the dealer advised me to use a blend of 50 per cent leaded fuel and 50 per cent unleaded, which I have done and the car is running well. Now that leaded fuel is no longer available, should I use lead-replacement fuel in the blend or should I just use unleaded?
Your engine is an all-alloy unit with hardened valve-seat inserts in the cylinder head, so it will survive on a diet of unleaded fuel without a problem. If you're concerned about it, have your valve clearances adjusted to specification, then run the engine on unleaded for six months or so and recheck the clearances. If there's little change, a thousandth of an inch or so, it's fine and you can keep running on unleaded. If the clearances reduce significantly, by three or four thousandths of an inch, then go back to running it on LRP or have the head fitted with new, harder valve seats that are available at most cylinder head specialists.