What is the best antifreeze for the D4 7U

As long as you use a good permanent anti freeze and use a 50-50 mixture that will be good.I,d use a brand name I think but may cost a few pennies more is all.I,d buy the anti freeze that you add the 50% water yourself as I think it might be a little cheaper.

Thanks.....thats what I was thinking. I might buy Cat if I go to the shop soon, I run Caterpillar in my truck.

It is very important to use anti-freeze that has the Special Coolant Additive (SCA). This is the easiest way to protect the liners from pitting.

Any good ethylene glycol antifreeze is better than none. I've been using Prestone, Zerex or Peak for many years in anything I have that needs it, and during winter here temps can and do drop well below zero. I wouldn't bother with the 50/50 premixed stuff, just get the full strength stuff and add the water yourself. A lot of folks use distilled water but I never have. .just clean tap water.

In my part of the world, humidity is high. I have a dehumidifier in the shop to keep machine tools from rusting when condensation happens. I use the water from the dehumidifier to mix with the antifreeze. Seems like it should be pure. I agree with buying full strengh but if you have bad water, it may be better to buy the mix to prevent nasty build up in your cooling system.