I have had my golf for 8 years its had good maintenance and a fills revive history by my dad. It's just passed its mot and the mechanic mentioned that the tappets were sounding a little loud so my dad who services and does work on my car flushed something through the oil and did an oil change afterwards to see if it would help. It was quieter for a few days after but is it coincidence that about a wen later when upstart the engine I now get a juddering engine and also grey smoke from the exhaust until the engine had warmed up properly. My dad is a good mechanic and he is mystified by the smoking and now considering is it the engine in its way out ?! Please help 😢

I have had my Golf for 8 years. It’s had good maintenance and a the record is kept by my dad. It’s just passed its MOT (Ministry of Transportation) test, and the mechanic mentioned that the tappets were sounding a little loud, so my dad who services and does work on my car flushed something through the oil and did an oil change afterwards to see if it would help. 

It was quieter for a few days after, but is it a coincidence that when I start the engine I now get juddering, and also grey smoke from the exhaust until the engine had warmed up properly? My dad is a good mechanic and he is mystified by the smoking, and now considering if the engine is on its way out.