I must agree with him that it is a myth. Most approved oils are formulated with very similar ingredients and methods and I don't believe that any one has any stronger 'detergents' than another. As long as it meets Mopars requirements then it is appropriate.

 

I've always run Mobile 1 synthetic. I've been told that high mileage rigs will burn more oil because they are thinner when hot. BUT... I have a 95 4.0 that has 250k on it and runs like new.

I believe it is safe to switch to any good quality oil. Personally I'd stick with one and not change around.

 

Not sure the actual Chrysler requirement for oil, but in my Walmart the Mobil 1 is not listed as meeting that requirement. The valvoline and penzoil synthetics do list the Chrysler requirement. I'm sure Mobil 1 is fine but because I have the lifetime warranty I won't use it since it does not say it is approved for Chrysler spec.

 

Its not a myth though it may not make as much a difference with the newer synthetic oils. Its the same with fuels. Different brands use different chemical makeups and do not always work together well. Fuels of different types and octane levels will separate in a gas tank giving you different performance out of a tank of gas as you go through it. Anyway my point although I may not have articulated it well was basically pick an oil and stick with it. It will be better for your motor overall instead of switching around every couple of oil changes.

Best of luck

 

Really funny how everyone started talking about what they recommend to put in the truck when the guy asked how you find out what the previous owner was using.
Personally I'm not sure how but it is fine to change to synthetic at anytime but don't switch back, so now would a good time to do so. If I had the choice again I wouldn't use synthetic, not a fan and not worth it. Only cause bloody 2010 wranglers love burning oil.

 

Wrong. You can switch back and forth between conventional and synthetic. Doesn't matter which direction you are switching. No harm will be done. All oils you buy today for vehicles is fully compatible regardless of synthetic or dyno.

 

The only way to know for sure what oil was used before is to send a sample to a lab. I will second the Mobil 1. I have used it for years and it has served me very well.

Sent from my Nexus 10

 

THANKS to everyone who has helped me w this.

 

I have absolutely nothing against Mobil 1 and use it in my wife's MINI. However, Chrysler says for the 2012 Wrangler that the oil must comply with Chrysler MS-6395. Mobil 1 does not but valvoline and penzoil do. I don't use Mobil 1 because I don't want to give Chrysler any wiggle room when it comes to honoring the warranty. I'm sure there is a reason Mobil 1 doesn't carry the certification. Probably comes down to not wanting to spend the $$ to get it certified.