Lotus Elan

Fuel Requirements

PostPost by: JP1 » Mon Aug 29, 2005 5:24 pm

I'm new to elans and trying to sort out a basic item, Fuel.

More specifically, do Elans S3/S4 need Leaded fuel?
I've typically found that vehicles from this era are designed to run on Lead, versus today's unleaded product.

What are your thoughts? Do you use leaded fuel, if Unleaded any octane boost or minimum grades are recommended.


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PostPost by: cliveyboy » Mon Aug 29, 2005 6:51 pm

Hi Joe
Unleaded fuel with an additive to replace the missing lead is the safe option.
The historic vechicle society did tests with a goverment testing agency to find the additives that worked best. try this link:-

The general opinion is that if you are only do very low mileage and do not use additives the amount of "valve seat recession" (VSR) will be so minimal that it would take years for a problem to occur.
If you are doing higher mileage then an additive will reduce the wear on the valve seats till its time for a rebuild.

I personally use super unleaded BP Ultima 97 RON. I have also used Shell Optimax.
I no longer use additives as my engine has unleaded valve seats
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PostPost by: brassrngfm » Mon Aug 29, 2005 7:30 pm

This has been discussed in the Forum before, so I advise to check the historical files. Net consensus: Aluminum head, Hardened steel inserts means you do NOT need lead additives. I've never used them, but my run time on rebuilt engine is much less than others.
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