i was gonna try and run my GTX convential in it this time then maybe swap over to there synethic after i get over 15k miles or so. iv just always been partially to them.

 

Do not use Castrol GTX in your Cummins. According to their website,Castrol GTX Diesel oil is not rated CJ-4. Certainly don't use the GTX oil for gas engines. As Jakebrake said, if you have the 6.7L Cummins you MUST use a diesel oil that is rated CJ-4.

Also, you may want to consider getting an analysis on your used oil when you change it. Some of us 6.7L owners have done an analysis of our used oil by sending it to Blackstone Labsin Indiana. Sabersix and I have both experienced fuel dilution in our oil, according to the Blackstone analysis.

 

If you towing heavy & often yeah... if your not towing I'd recommend waiting until 25k before switching to synthetic in the motor.

 

thats some good info there. im gonna have to ask the dealer i take it to to tell me what kinda oil and what not its gonna put in the motor and all that. wow thanks