[Colster]

Hi Adrian. Does the oil pressure light work correctly? Lights when ignition on, off when started? Could be hydraulic tappets not yet filled up. Check all auxiliaries and belt not catching.

 

[Colster]

I expect your tappets have drained of oil due to reduced use. They may well bleed with more frequent use now.Engine oil will not degrade in your shed.

 

[Colster]

Sorry to hear this.

My bet is on the belt tensioner. But also look at this thread if you haven't already...

https://www.x-trail-uk.co.uk/viewtopic.php?f=9&t=23218

You need to address this now to prevent subsequenrial damage.