Recommended way to draw an engine oil sample?

[plyonsMC9]

Good morning bus folks!
What is the recommended way to draw an engine oil sample for testing? 

I was going to slip a small tube down the tube used for the dipstick, but possibly I should instead loosen the drain pan plug?  My concern there is that the sample would just be oil off of the bottom of the pan. 

So here I am looking for some guidance.  Thank you!,
Phil

[luvrbus]

Do it with a suction tube if you don't have a oil test port you never take a sample from the drain plug ,most series 60 in the commercial world have a oil sample port ,if yours doesn't have one installed Trico is a good manufacture so is CAT of oil sample ports lol you can pull a sample and never get your hands dirty with a sample port

[plyonsMC9]

Great advice - thank you Cliff!  I'll look for the port.  If I don't have that, I do have a suction tube, will just need to modify a bit to get through the dipstick tube.

Best Regards, Phil