One headlight isn't working anymore. Does anyone now which light bulb fits? Is it H3? And is it easy to replace?

Also i noticed, that when idling, the engine is (of course) very silent and quiet. But sometimes you get a very small "shock" from the engine. What can this be?

It is now cold here and in the morning i saw all the cars with frozen windows, but my Lexus didn't!!! but how? Is it good isolation or something?

 

You don't give the year of your LS400 but the link below gives the details you need the top one in the list is for the bulbs and the 2nd one for headlight removal to fit the bulb.
http://www.lexls.com/tutorials/lighting/

Difficult with the engine problem is the servicing up to date and the ignition system all good?

 

Sorry, i have the 1995 version...

 

for a 1995, your headlights are H4, very easy to replace. just have to remove the intake covers with a 10mm to access them. unplug the connector by squeezing the sides and pulling away. undo the plastic D holder by simply pushing down and out on the tab. peel the rubber dust boot off and over the end of the bulb. locate the locking tab and push in then swing out to unlock the bulb from the housing. do NOT touch the bulb glass with your bare hands! i recommend always replacing bulbs in pairs.

as for the windows, your glass may be coated with rainX or something to keep it from fogging or frosting. it could be waxed.

 

Thank you!