M20 Idle Change

[Maxtek]

At the beginning of the week my M20 was idling at around 1200 RPM and the last couple of days it's decided to always idle at 8-900 RPM.

I've read on the Wiki that idle's should be around 1000 when cold and 7-800 when warm but the weather hasn't changed much at all for the past couple of weeks.

The engine also sounds healthy, besides from the tappets becoming louder (or me just noticing them more).

The only things I've changed recently are, a new battery about two weeks ago and I used non-premium fuel compared to premium which I had been using every time before.

I don't know if this is something to worry about or not, just thought I'd check as I'd much rather carry out preventative maintenance rather than wait for something to die and then have possible further issues.

[Brianmoooore]

I've read on the Wiki that idle's should be around 1000 when cold and 7-800 when warm but the weather hasn't changed much at all for the past couple of weeks.

This refers to engine coolant temperature, not the weather!
Sounds like the car has been faulty (TPS? Throttle cable too tight/sticking?), but is now working correctly. Your rev. counter is not a precision instrument, so it's probably exactly what it should be now.
Premium fuel gives no advantage, and makes no difference whatsoever.

[Maxtek]

I haven't noticed a single fault other than this apparent fault in the short amount of time I've owned it. There may well have been some issues recently that the previous owner didn't tell me about though, which wouldn't be too surprising.

I was referring to the engine temperature (although not the coolant) but thought that the weather might effect it to an extent.

Is there really no benefit to running Premium fuels? Not even from the likes of Shell? I've read about some nasty/more additives being used in non-premium supermarket fuels and heard a few stories. However this is the first car that I've actually thought about which fuel I use.

Guess this is a non-issues then, thanks Brian.