When I got my last new truck (Gas Engine) I was still pretty old school when it came to oil changes and maintenance in general so when I saw in the owners manual that you could go over 7000 miles between oil changes and not void your warranty I was shocked, but also intrigued
so I had an analysis done by these folks just to prove it myself.
Well I'm happy to say that that led to me testing the threshold of the Mobil 1 extended drain Synthetic after my warranty had ran out and now with my driving style and geographical location I only change my oil every 12 thousand miles and have the analysis to prove the wisdom in doing this so anyone interested in having their oil analyzed you can get free kits from
Blackstone labs. They will send you a collection kit for free and then it's only $22.50 to get the analysis done. For those of you who are running an extended drain (5000 miles +) for $10.00 more they will
give you the TBN (total base number) which measures the amount of active additive left in a sample of oil.
Everything you need to read and understand your analysis is here from
Bob the oil guy and by the way, Blackstone labs also will test your tranny fluid for you.