Dip stick- What side to read?

When the engine is stopped for a length of time all the oil has run down into the pan, so this mark on the stick is the higher one. The engine running one is again straightforward; the dipstick is probably shrouded into the pan so that splashing oil won’t give a false reading. Anyway, the oil is in circulation, some on the top of the head, some on the cylinder walls, etc and not in the pan, so this reading will be lower than when the engine is stopped. It’s basically a convenience feature.

I run a CAT 140-G grader made in the mid-1980’s. It has the double sided stick and when you are running back to back shifts like when plowing snow, it allows for the oil to be checked without having to shut down for a long period of time to check the oil.

I didn't know IH did that on farm tractors (never had anything newer than a 450D), but if you think about it, the oil level with the engine running is more important than with it stopped. As long as there is sufficient oil in the pan to avoid the sump picking up air (entrained or otherwise) and to get rid of the heat then the engine probably has enough oil. I'm not an engine designer but I'd bet that the running level is what they design for.

It is interesting to note 130 and 230 have this feature. Your 450D is the same vintage and from the same series. Would have been a lot quicker to shutt 130 or 230 down for a noon time oil check than a 450D. 130 is the only tractor I've ever owned from the 30-50 series. My brother has a 230. I'll bet I know the secret behind this. There were countless C-123 engines used on amusument rides like ferris wheels, merry go rounds, etc., etc. Those guys never shut them down from morning until late at night.

We had an old engine which I was told the lower petcock was for checking when the engine was running but the baffle inside must have been broken. I believed that for years.

Twenty years ago I ruined a good shirt pulling the dipstick on a running Cub. I would have sworn the Cub engine on our old baler could be checked with it running, but this one couldn't, and everybody around got a good laugh at my "stupidity".