When I'm idling at traffic lights, the engine revs seems to drop very slightly every few seconds, and then come back. The drop is very small and the rpm needle moves only very slightly, but it is still noticeable

In another thread someone said that rpm drop when idling means a leak.

Should I be concerned about this?

Might be the aircon switching off and on and loading the engine? Try it off manually.

Might be the aircon switching off and on and loading the engine? Try it off manually.

I only have the basic aircon and it's been off since winter began. But thanks for the suggestion!

I've seen a lot of VAG petrol engines doing this, but not the diesel. No idea what could be causing it, but it doesn't seem to get worse or damage anything either.