Feel it's time to do a complete coolant service on the coach. Understand that we must exercise care in choosing coolants that are Cummins approved and compatible. Also understand there are some other misleading products that could damage the system. Would look forward to opinions on experiences doing it yourself or by having it done by a qualified Cummins shop. I'm reasonably handy in doing most of the scheduled maintenance myself. However, while the shop would of course cost more, with either choice, most important to me is to get it done right. My DIY concern is the unknowns of the potential pains associated with the penny wise pound foolish route.. Look forward to getting your thoughts on this.
I do mine on the coach and diesel trucks... drain keeping the animals away from the antifreeze and refill to -20 or whatever the area's weather you will be in calls for... my old cat takes green but I have some late model ISX cummins that take the red.. I don't like and don't buy the pre mixed antifreeze because a gallon of it cost as much as straight antifreeze making it twice the expense.
I know you don't have the two cycle Detroit Diesel engine, but for the benefit of other readers who do, your local Detroit Diesel dealer has a test strip that will tell what chemicals to add to the coolant, and they probably have the additives in stock. In my case I was told to add Detroit Diesel "Power Cool 3000" which is brilliant pink colored, so there's no question that it was added because it's easy to see in the coolant. Detroit doesn't require coolant changes on two cycle engines, but you do have to test the coolant periodically and add chemicals as needed.
I chose DIY. But I have trust issues with others doing work for me, and do most maintenance myself. Two years ago, in my mechanical 8.3, I replaced the old stuff with the orange OAT stuff. I did a good flush, which I figured a shop would not do that included the 36 feet up to the heater in the front. Now the engine runs 10 degrees cooler than it had for the eight years I had operated it, and I have one less filter to change each time. We have dogs and so do the neighbors. Properly disposing of the old stuff is essential. In another year, I must test the coolant, and possibly add some extender. This was one of the easiest and effective maintenance projects I have performed on our "Bugcatcher". (Other than installing solar panels, changing AT fluid and filters, replacing air bags, and with wife's help of replacing an inoperative "alternator" for the generator, and so on.) andy1