Running an oil that doesn't carry the specifications required for your engine is more harmful than mixing two generations of the same oil. All motor oil is required to be able to be mixing with any other motor oil. This is how people can switch from one brand to another without full flushing out the oiling system on their car. Running an oil that doesn't have the right specifications can cause a shortened life for the engine. How long that may take to impact your engine will vary depending on what oil and what engine.
There are some interesting threads where people ran the wrong spec oil and got sludging and other threads where different oil was specified to protect bearings, etc. I haven't seen one that has resulted in instant seizing of the motor or explosion. However, if I do, I hope they include video and pictures.
You will probably be fine using the mixed oil. In the long run, get into the practice of putting the right specification oil into the engine, as this is a better practice.
Welcome and don't let people's bad humor or apparent abruptness keep you from asking your questions and satisfying your curiosity. I also suggest using Google to site search BITOG, as it works so much better than any built in search. This is often the case in many forums.
Cheers.
Originally Posted By: Crobinson16
Actually neither version has the " certification " my engine requires.
I guess my consern was if they are in fact different base blend's weither it GTL or Visiom? , forgive me for my lack of knowledge on oils, I was under the impression they may be totally different. And I didn't know if that would cause a mixing problem or something else down the road ,Im just not that informed as some.
Originally Posted By: Coprolite
IF your car blows up, you didn't hear that it was ok from us.....
It will be fine as long as the new Mobil still has the certifications required for your car. It doesn't for mine, so I am going straight to Castrol without one drop of M1 ever touching the car.