jim wrote in news:BoCdnR030_d3kpDRnZ2dnUVZ snipped-for-privacy@bright.net:
Definitely. 2,500-mile-old oil is darker and easier to see on the stick. I do find it a bit difficult to locate the top of the "meniscus" with brand- new oil, since it's so clear. It is possible that my second check is more accurate than my first, for this reason.
A fresh batch of Mobil 1 went in this evening. I took the opportunity to try and determine exactly where the "live" area of the dipstick was in relation to the oil pan.
The bottom of the dipstick is, as far as I can measure, about an inch below the bottom surface of the oil pan mounting flange. A bit below that point is when the pan's "shallow" area suddenly takes a dip into the "deep" area.
The "shallow" area slopes downwards maybe 1/4" from the flywheel end to the "deep" end, maybe a 6" distance. It then takes about a 12mm radius and then heads straight down to the drain bolt.
Based on these observations, I believe the oil level does drop fairly linearly, since there is no drastic change in oil pan shape from upper mark on the stick to lower mark on the stick.