I'm planning on buying a oil sample kit from work to have my oil tested when I change oil next time and was wondering, whats the best way to take a sample? I'm guessing you wanna have it good and hot. do I just drain my oil and catch the last little bit coming out of the pan, or must I fill the bottle mid-stream? I'm just interested to see how this newer CJ-4 rotella held up in my truck and now long I can go on an oil change. Probably not to long with that stuff I'm guess.

 

I would change the oil like always and take the sample form the bucket or whatever container used to catch the oil. If you think about it the oil is constantly being circulated while the engine is running. So i don't think you will find any difference in your test results when you abstract the oil whether it's beginning, mid, or end.

 

I believe most sample kits come with instructions, IIRC mine said midstream, ensuring not to let any contaminates get in the sample. The kit I bought was from Cummins (22$)