I have a Thinkpad T420 – now 2 years, 6 months old. Started to notice the fan seemed a bit noisier than normal and the CPU was reporting a temperature of around 60deg C, even when the machine wasn’t doing very much.
As suspected, 30 months of usage without a clean is a little bit too long. Cleaning a laptop fan can be fairly straightforward – this took just two screw removals. Of course, always seek advice and YouTube videos if you need help to do yours! 😉
After the procedure, my laptop runs about 10-15deg C cooler and is much quieter.
(Warning, images are grotesque scenes of mostly human skin. Some microscopic lifeforms may have been “damaged” during the making of these images…)