When I checked the Envoy's engine oil yesterday morning, the color was close to lemon yellow. The oil (M1 5W-30 ESP) had a little under 6,000 miles on it and was full. I run Euro V gasoline, which is a perfect match for this oil.
Earlier in the evening, something work related came up and I had to respond code 3. The RPM range was 3,200 - 6,000 rpm for roughly half an hour - an average of about 3,200 - 3,500 and up to ~6,000 rpm under WOT after I had to slow down for vehicles slow to yield. Coolant temperatures varied between 184 F - 190 F - I think my thermostat (190 F) may be due for replacement. ATF temperatures varied between 150 F - 163 F.
There was barely a change in the OLM afterwards - it dropped from 52.9% to 52.5% - but the oil was considerably darker in color (no change in oil level). The oil's now more of a dark caramel color. Color is not always an indicator of oil condition, but would it be safe to assume that 30 minute "Italian tune up" broke quite a bit of carbon loose into the oil?
Earlier in the evening, something work related came up and I had to respond code 3. The RPM range was 3,200 - 6,000 rpm for roughly half an hour - an average of about 3,200 - 3,500 and up to ~6,000 rpm under WOT after I had to slow down for vehicles slow to yield. Coolant temperatures varied between 184 F - 190 F - I think my thermostat (190 F) may be due for replacement. ATF temperatures varied between 150 F - 163 F.
There was barely a change in the OLM afterwards - it dropped from 52.9% to 52.5% - but the oil was considerably darker in color (no change in oil level). The oil's now more of a dark caramel color. Color is not always an indicator of oil condition, but would it be safe to assume that 30 minute "Italian tune up" broke quite a bit of carbon loose into the oil?