Look in wall mart, and if u want the best oil for the buck get the mobil one for high mile and older engines, it is a low and high number u want, the high number is good for engines that are made like the ol dodge, a little looser, as oil is really a simple thing, the 5/30 ranges are for new very tight motors, (and colder climates extremely cold)as the tighter tolerances will not allow a thicker oil to lubricate those tight tolerances during start up mostly and rob that engine at a critical time, the more worn an engine is the more u want a heavier oil , it will stay in the motor longer and help lube those worn areas . it is hard to make a decision today because they market to such an exact audience, but the real basic rule is simple, all oil mixes oh yes it does, and any i mean any oil is better than no oil, to get home. and as for the military using straight 30, remember that is for such a wide range of climates it was a good idea, now with the 15/ 40 this oil does a wider range of things and is just up to date, any oil is good if U service it and keep it clean, if U really hammer your vehicle u need the better mobil one types, or a heavier oil, the "W " stands for "winter, meaning a cold climate, so the low number is what the oil will change to by itself when it is cold to lube those places a thicker oil would not, and when warmed up the change over to a thicker state occurs. now for more info, a detergent oil is for motors with a filter. the detergent cleans and breaks up deposits and sends em to the filter, a motor with out a filter compressor etc,. u want to not use a detergent the crud is better to stay where it is. it also is recommended to have more frequent oil changes with a non detergent, also if U want to clean a non filter u can run detergent and change while still warm to clean her up a bit, oil is simple, read the labels write down some questions and call the 800 numbers on the can, i have been for over 30 years, when i offer advise on stuff like this it is from years of techs saying the same stuff from year after year and different product techs agreeing, thats when U get the best answers, never ask just one guy and think u have the answer,
good luck....OH the rottella 15/40 will serve u well for longer than u will be around, it is a quality product, and all around just a great choice...also...
