The fact is: Synthetic oils are simply more refined. The abilities of motor oils to lubricate and suspend dirt when they are brand new out of the bottle are the same between naturals and synthetics. the speed at which they become dirty an viscosity breaks down is what separates them. synthetics last longer, they do not lubiricate more or better, just for longer within required specs. motor oils have basic requirements they all must meet and nearly everything being sold today meets the requirements. from the 1.00 qt all the way up to 12.95 a qt for Amsoil or royal purple.
If you are using naturals, change it every 3k
If you are using full synthetics, change it every 5k
DO NOT BELIEVE THIS 15k OILS BULLCRAP THOUGH.....never go beyond 7k, its not worth the risk
This being said, I personally perfer Mobil1 full synthetic 10w-30, I run Amsoil or Mobil1 full synthetic 15w-50 raceweight in my modified SRT-4. I choose oil based on what the vehicle will be doing, my KJ is a commuter car, the Mobil1 full synthetic 10w-30 is fine for it and changes every 3-4 k. My SRT4 gets Mobil1 full synthetic 15w-50 raceweight because it rev's high near redline A LOT and the motor runs hotter and its turbocharged so the 15w-50 has a greater temp range and it gets changed based on visual condition or at 5k.
Craig + Elizabeth
ASE Certified Professional AKA: MacGyver
07' KJ, 2.5" lift, skids + hooks, Moab 16's and MTR's, safari rack, 4 PIAA's, AZ pinstripes,