Thanks for the info I will try those testsAre you losing water? Some models if fuel pump leaks can put diesel fuel into the oil.
Take a sample of the oil and put in a clear jar or glass and let sit. Then you can see what separates out. Another test if water is drip some in a warm
Pan does it sizzle and steam? Be careful if you try that though since the steam bubbles might burst spraying hot oil.