I have a 01 chevy blazer v6. This started a few days ago, my oil gauge stayed at a constant 40-60. And now when I start it and start accelerating my oil temp goes almost up to 80 and then back down, but when it's been running for like 10min.'s it's fine, the when it's ideling it's down to 30. I checked the oil it looks good and is at the level it should be, why is it all of a sudden fluctuating so much?????