insufficient time for the oil to universally heat up to > the boiling point of contaminants ( which range from ~ 170 deg to 212 deg) for long enough to boil them off.
The way i see it, motors go through 3 phases:
1. cold when they run rich, generate lots of washdown and H20 and therefore actively dilute the oil
2. > cold but < boiling where the contaminants remain, btu little added harm is being done, and
3. > boiling wheile the oil's condition is being improved
The depends on time, ambient temperature, and how hard the car is run.
My personal take is i need to see the water at stable temp (186) for some time before boiling is happening. I wish we had an oil temp and pressure gauge.
In my S6, which has one, oil lags water significantly, and never reaches 200 deg except on track. but fortunately, local oil temps are much higher.
(is that a good thing? i suppose its mixed)
Under most circumstances for me that means <15 minutes is bad.
Note that my dilution is very very low. Note also ( i hate to misquote Marc today, so let's hope i'm right) that Marc had one sample with 7.5%. We'll assume that was an outlier.
here's my real answer: i take my bike to the gym not only for the cardio benefit, btu to leave the car home for the 2+ mile ride. I try to cluster shopping - e.g.; on the way home.
Grant
Grant
gee-lenahan-at-gee-mail-dot-com