Hi,

Dunno if this applies to your car or the OP's two, but it's good
practice to protect your bulbs from corrosion where they contact the
socket. The auto parts stores sell some kind of overpriced "bulb"
grease, which is probably just the equally overpriced "dielectric"
grease, to help. Just apply a very thin film to the center contact and
the metal housing of the bulb. If you don't want to pay their price,
plain ol' Vaseline has worked for decades...

Some bulbs are a bit voltage sensitive, so a loss of voltage thru some
corrosion may be a player w/ your cars' bulbs going out. Then again, it
may not.

Rick