Anyone here running a 579 ultraloft MX13 with autoshift? Any pros and cons,problems,or fuel millage???
I have a 510 Paccar, 12 spd with 2.79 rear ends. I like it, this is my second 579 with the 510 Paccar I’ve had. I ordered the Ultraloft thinking the closets would be bigger than my last bunk. The closets are the same size but the bottom mattress is larger. Overall I like it. There’s a ton of room and plenty of storage especially if you don’t use the top bunk and take that mattress out. Lifetime mpg on paper is 7.38 on 199k miles. I have a larger gap between the cab and sleeper than most so your average wheelbase 579 will do better on fuel than mine.
My 579 is a mid roof with a 455 EPA-13 MX-13 and 13speed but should be a good data point regardless. I have had the reverse experince of long here. If you can think of something going wrong, its happened. If there is absolutely no chance of it blowing up.....it blew up. MPG is around 6-6.5 as a rock bucket which is pretty good. Would likely be getting in the 7.5+ range as a dry van and roof ferring on it. They are slow as dirt and underpowered as hell though. Even a higher horse motor is going to be a dog in the hills compared to many other rigs. Big thing with MX motors is the motor itself is rock solid and a huge percentage of them hit the 1 mil no rebuild mark. Frankly if i could get one without all the emissions crap bolted on id not hesitiate for a second. Hell even one with just an EGR would be an amazing motor. But the emissions on the older engines at least is....iffy and you need to stay ontop of that maintaince schedule like crazy. Also as you get into the 750-800K range the steering racks and leafs in them tend to need to be entirely replaced. They start to wallow out and crack from stress on them. Or at least mine did though the pete tech says its pretty common on the 579.
