Oil Dipstick Readings Vary

[WarrenD]

OK, this is weird (I seem to start out like that often!) I checked the engine oil yesterday AM before heading out to my first public appearance with the M37 guntruck. Oil level was dead on the full mark. I checked the oil again this AM and it was down almost 3/4 qt, almost to the add mark. Now, I don't have any significant engine oil leaks, nor was I burning oil. I've been aware of some strange readings in the past where it was down, I added a 1/2 qt and a week or two later when I checked again, it was overfull according to the dipstick. I've been concerned about a possible leaking fuel pump as a result of that observation.
This morning I decided to recheck and when I did, it was down 3/4 qt. I checked again and it read full. Checked again and it's down 3/4 qt. What I found was that it depends on how I put the dipstick back in, so my question is, which is correct? I don't want to over fill, but I don't want to run 3/4 qt low either. Looking at the dipstick everything seems normal and it locks down tight in either orientation. I do notice that in one orientation the dipstick makes a clanking sound (sounds like the bottom of the dipstick hitting something) when I twist to remove it and the other orientation it seems quiet.
Is this normal and which reading is correct?
Thanks again, you all have been very helpful and I greatly appreciate it!

[WarrenD]

I think I have the work around, drain the oil , change the filter and put 6 qts of new oil in. As long as there isn't an accululation of sludge in the pan, that should give me the proper dipstick reading. Any flaws in this logic?

[m37jarhead]

Warren:
You're on the right track. You've got to have a base line to start with.
Change the oil and filter; refill with six qts. then run the engine and let it cool off.
Try both dip stick orientations to see which one gives you a "full" reading.
Odd that rotating the dip stick now gives you such a big difference on the oil level.
No opinion on that.
JB