Timing chain tensioner
 

I understand my sister's 08 Clubman (non-turbo) is prone to timing chain issues.

She has a little over 80K miles and I'm thinking it might be a good idea to replace the timing chain tensioner just to be safe. My concern is whether changing just the tensioner alone is ill advised - New tensioner but original chain and guides.

The car runs fine: I advised her sometime ago about not following Mini's oil maintenance schedule. The oil is changed every 5K.

Thanks in advance

The N14 engines (2nd gen turbocharged engines) are the ones that are known for the "death rattle" from the timing chain tensioner. Yours has the N12 engine - not even the 2nd gen Clubman which is the N16. The naturally aspirated engines are not 'known' for having timing issues.

Here is info on the R56 N14 timing chain: MINI Cooper R56 Turbocharged Engine Timing Chain Guides Replacement (2007-2011) | Pelican Parts DIY Maintenance Article.

Now, that being said, it doesn't mean that it wont have any timing issues in the future as it might. So, you can replace the timing components as a preventative measure. I'd do the whole timing set if you're going to do the job.

Yes, oil should be changed every 5k, so good call there. Make sure she also keeps an eye on the engine oil as low oil can cause internal issues. We have a timing chain kit by Febi here: 2008 Mini Cooper Clubman Wagon - Camshafts & Timing Chains - Page 1 that has just about everything you'll need/want for the job. Let me know if you have any questions.