Hi,
this morning when starting the car I heard a very loud tapping noise coming from the engine bay. It sounds it is a valve tapping noise. The noise disappeared after 2 minutes or so. I know this can be totally normal when cold but I'd like to know what is causing that sound. It is a lack of lubrication when the engine is cold and the valve tappets are not properly oiled? If so, should I use a thinner oil for winter (now I use 10W40 because my engine has 217000km, S40 2.0 140cv phaseI)?
I also heard such problem may come from a worn or stuck valve lifter. My actual oil (Castrol GTX Magnatec 10W40) has a high ash content. Is it possible that it has clogged a lifter and cause it to make noise? Should I then flush the engine oil to remove the deposits?
Thanks
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