Originally Posted by P Kennedy

Sure Dodgediesel I'll take a shot, 2nd CTD 2001 HO 239,000km on truck. I have run synthetic 15-40 since 50,000k in my truck with 25,000k oil changes and the Amsoil or now Donaldson filters they sell. Truck will usually start down to -29C without being plugged in overnight, lots of idle time in the winter at elevated rpm's. Magically I also live in the same local and can show the oil use in a relative climate. Truck weighs 8000+ all the time and up to 29,000lbs loaded no problems except if you have a leaky spot it will find it's way out. Use Amsoil as the warehouse is in Edmonton and open until 8:00pm Thursday nights and I pick it up on the way home from McMurray where I commute to work. "I can't justify the cost" is another foolish concept as the engines here typically run longer continuously and are subject to more severe changing work conditions than in other places with extended or neglected oil change intervals. The "oilpatch" does not have a speedylube on every corner and when we are busy as you know money is made on the move not sitting in town coffee cupping the day away. Everything is Amsoil except the tranny(6 spd) including my non-stock Detroit Locker- it won't work towing- rearend. Amsoil in my opinion does not yet have a proper oil for the 6 spd units but Redline does available right here in sunny Alberta. Call me this isn't the only diesel around here on "Amsoil" with excellent results----and a way we go, proceed flaming. PK

Originally Posted by dodgediesel

I was looking for a 15/40 synthetic and nobody really carries this.. Everyone seems to carry a 5/40. Is it ok to go from a standard 15/40 to a synthetic 5/40? What do most people use after initial break in with a standard 15/40???