Had two festoon bulbs go just before 2yo and 30000miles- just wondering if that is the norm or do I have too high a voltage. All my rear lights including the number plate festoons are on permanently in conjunction with my front DRL. I chose that set up from new. I've ordered a pair of long life bulbs to replace my cheapo replacements. Had one Osram Silverstar dip go in the same period- now replaced with the current longer life versions.

Battery voltage is 14.1V at idle, a few minutes after starting, with nothing else apart from the DRL on. Should I check again after longer use or with a heavier load?

The top of the battery has some kind of warning indicator. A label says if it is clear or yellow then replace battery. My indicator looks black- or is that clear????

I've never noticed a big variation of headlight brightness with engine revs such as your describe.

Check the battery voltage when the engine is running , should be about 14V above tickover.

Was my own advice last year. Mr Memory I am not.

Start worrying if it reaches 16V

Got a long life pair of Mazda festoon bulbs from an eBay supplier for £2.75.

Tried to buy a pair from Autobulbs but they sent the wrong ones. Many emails later they still had failed to replace them with the correct ones. Got my money back- eventually.