Does 1 watt make a difference?

[type-r]

I bought a set of tail light bulbs P21/5w however the manufacturer handbook recommends P21/4w. Does 1w make a difference in terms of safety / electrical fire etc?

[type-r]

Ok cheers for the info, very useful and interesting. As the fitment lug is offset 30 degrees from the plane in 4w, 5w won't fit. Cheers for that.

[type-r]

Just to be clear, the reason why I went for a 380 instead of the recommended 382 in the shop, was that 382 had a single contact whereas the bulb I removed from the car had a twin contact. I went for the twin contact 380 but didn't realise the lugs where offset as they are shown in the pic above!