My Mazda has been consuming a lot of oil since recently. Everything is dry in the engine room. Before 10,000 km 5w-30 (although I had ordered online 10w-40!) was tipped in by a workshop and is now loud measuring rod empty.. Even before 10w-40 the oil consumption was so high. My question now, can I just tip 10w-40 on top of it? It should be very little 5w-30 still in there, hope that that doesn’t matter. And for increased consumption the spark plugs came into my mind. if. Unfortunately, I can’t find one on the Internet that fits my engine! Most of them are suitable for the year 2000 or from Bosch. My 98 year of construction can help me? Should NGKs or Denso be.