Back in the 80's or 90's at caterpillar I could by a product called Nalcool they tell me it is not available,does anyone know of a replacement for this product used to prevent calvation of the piston liners

Go to your local NAPA. They handle a very comparable product.

Nalcool and Nalprep! I haven't heard those names since the 90's. Great stuff. Had some engines torn down and the mechanics said my liners were perfect. The stuff must have really worked. I don't remember WHY we had them taken apart though. LOL. I do not understand why they do not offer coolant treatment/filters for current engines, or am I mistaken. JM

Cat SCA [beet juice] part # 3P2044 1 quart bottle $9.13 from Cat
I add a quart every 250 hrs at oil change.

Some of the antifreezes have SCA mixed in it. Wix calls their treatment Wix-Cool. John Deere has a coolant treatment also.

Yes, I use the standard pink Cat coolant also.

i use a product called eco cool aoc1000 by australian organic coolants it has a life of upto 6years/12000hrs and is suitable for all vehicles that dont need freeze protection at a mix rate of 7.5 percent with demineralised or distilled water. it has anti corrosion anti cavitation properties.

they also have a specific diesel coolant aoc 2000which is anti cavitation anti scale anti corrosion anti electrolysis film forming protection for engines with cast iron blocks and cooling systems

Do older engines, like in our older D2's, etc. need any of these modern antifreezes or additives? I use regular green Prestone @ 50:50. It seems like the cooling systems on these machines were originally designed to run on anything from pond water to alcohol. Growing up in the 60's, I never heard of anyone using diesel specific antifreezes. If they are better or prevent a problem, I'll use them but I always assumed they were only for the more modern diesels.

Always good to use a rust preventive.