Spark Plug Mix Up?

toooo big a gap

otherwise no excess oil or carbon

not bad

 

Theories on why the factory plugs are different have been kicked around for years. One day I went up to the parts manager at a large Toyota dealership and asked him. He said it's done for warranty purposes. If someone blows the engine, and it only has, say only 500 miles on it and the plugs are different than what was originally installed, they can say you voided the warranty by doing unauthorized non dealership or modifying work on it.

 

It’s all about the contracts with Denso and NGK.

 

I don't know. The Japanese all work together more. They are probably only spark plug makers in Japan and they spread the wealth.

 

That's not how warranties work though. Changing your own spark plugs doesn't void the warranty.

 

Asian auto manufacturers frequently source products from multiple suppliers. This ensures suppliers compete on cost and quality as well as ensuring backup sources should needs arise.