I'm not sure about a chemical test. It could be a sniffer test of your oil to see if it has mixed with antifreeze.

If I was in your position, I think I would look for a reputable shop that is known for quality work. I would talk with that shop to get an idea of what it will cost to do the job right. Then go to the dealer and ask them also. Although, it may cost you a lot now, it will be something that you should never have to worry about again.

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2007 Suzuki Vinson 500 4X4
2007 Toro 6.5hp
2006 BMW X5 4.4 ltr (his)
2001 BMW X5 4.4 ltr (hers)
1994 Honda XR650L
1984 Honda XR80

"Beer is proof that God loves us and wants us to be happy."
Benjamin Franklin