I won't bore you or anyone else with the why, but I'm a huge Mobil oil fan... They do have a MS-6395 spec oil but it's their Super Synthetic, not what is usually found in an O-Reilly's.
For others, and if you are curious, I wrote about more here -> http://sevenslotsyndicate.com/blog/k...ne-oil-change/
My comments on this spec and oil are at the bottom but are notated in the article.
"Jeep recommends oil that meets or exceeds MS-6395. This is an old and outdated specification and it can be tricky to find oil with it. The type of oil we are using in this write up has NOT been tested for MS-6395. It does however meet or exceed the required specifications. If you are concerned about warranty ramifications, Mobil Super Synthetic does have MS-6395 approval but was not available for us locally. It also is vastly more expensive."
Actually, Chrysler/Jeep only
recommends MS6395 certified oil that meets Chrysler's standards. They do not say "recommends" oil that meets or exceeds". The key words are "has not been tested" which is part of the requirements for MS approval process.
Actually the claim of it being an "outdated specification and it can be tricky to find oil with it",
is not completely accurate.
I have had no issues finding oil in the 5/20 MS requirement.Not all oil has it but common oil like Pennzoil or Valvoline have the MS standardin the 5/20that my Cherokee uses. In fact a different weight of oil in those brands may not have the MS 6395 certification.
Also I do not understand "outdated specification". Basically I read that entire statement as justification to use their oil regardless of the lack of Chrysler's MS6395.
But to be clear,
There is absolutely nothing wrong with Mobil 1 oil and I believe it will do nothing to impact your warranty or the engine by using it but there is that small issue of MS6395 not being certified for Mobil 1.
There is also a difference in word semantics in the manual. That is "recommends only" vs saying "requires" MS 6395 is a big difference when it comes to warranty issues in my opinion.
But in the real world with available oil brands that do have the MS6395 certification I see no reason to vary off to the ones that do not carry that certification. Pennzoil full synthetic, which I consider a high quality oil, which I do use carries the MS6395 on the label.
I would just suggest that Mobil 1 get on the stick and certify their oil for us instead of minimizing the semantics in their statement. It is either MS6395 certified or not. If its not on the label then its not certified, regardless of what they are trying to say.