Antifreeze

Yes, as stated in your Caterpillar manual (there is a section on coolants), SCA is called for in the 3126/C7 even though it is a parent bore engine.

15K miles? I would not worry about changing it out. But if you are worried just take it to a Freightliner shop or a Caterpillar shop and they can test it.

They all need to be tested. Check with CAT and you can look at it. If it is Red, it is extended life, good for 350,000 before you put in a bottle of additive.

Schertz wrote:
When in doubt, change it out.

Coolant cavitation is destructive the diesel engine.

You can purchase a bottle of test strips and determine if your coolant is satisfactory.

The OP's C7 Cat is not a wet sleeved engine and I don't believe it requires SCA replenishment or testing.

When in doubt, change it out.

Coolant cavitation is destructive the diesel engine.

You can purchase a bottle of test strips and determine if your coolant is satisfactory.

Most antifreeze types list a 5 year use life regardless of mileage. If your chassis is a 04, your pushing 9 years. I would change it if it were mine.

No question. At 8 years old, even if it were an OAT-based extended life coolant (which was NOT fit by any chassis maker) it would be time to change.

For regular coolant, 3 years is normal life. Perhaps push that a little, but not to 8 years.

BTW, Caterpillar also recommends changing the thermostat(s) at 3 years, so add that to the list.

If it has been in there since 05 it probably needs changing. 8 years is a long time.

Not many miles but a lot of birthdays. You could always pull a sample and get it analysed. Cat should be ale to do it for you.