bmwe21.net forums

Again I'm showing my age here!

When I had my e21 320 unleaded fuel was just becoming available, I ran it on 4 star of 5 star fuel if I could find it. When Unleaded came in the advice from BMW was to run every 4th tank of fuel as 4 star leaded to stop valve seat recession. In my mind the valve seats have steel inserts and there shouldn't be a problem, but what are people's experiences with an unmodified engine?

Many tahnks

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BMW use alloy heads, so hardened seats are fitted anyway. Added to which, unleaded was available in mainland Europe long before we got it here. Best to use super unleaded or an octane booster to stop pinking though, or possibly retard the ignition a tad?

Done both my 320 and 323 in on unleaded back in the 90's even after bmw adjusted it .
Never again.
Now i always add addative just as a safeguard.
My rule of thumb is if no cat give it some addative .

Always running on unleaded here, but always trying to use highest octane available. Especially in Italy you can run into some low octane stuff, for these cases I carry an octane booster but other than that, no additives.