Antifreeze/Coolant Change Intervals
 

I have a question for you guys that I'm sure have more experience than me related to car things. I have a 1978 K5 Blazer that I had the antifreeze/coolant changed in 2022 with Prestone's longer engine life coolant (10 year or 300,000 mile guarantee). Now I know I'm never going to approach 300,000 miles. My question is do you think this antifreeze/coolant would be alright to leave in for say 5 years? I've often heard that the anti freezing and anti boil over properties last for decades. It's what is added that wears out over time or mileage, such as anti-corrosives and lubricants that require the frequent changes. My owner's manual says to change the antifreeze/coolant every 2 years, but I'm sure today's are much improved over 47 years ago. I drive the Blazer no more than 500 miles a year.

What do you guys think? Any advice appreciated.

...

Myself, I would change it out after 5 years. It's not a hard job to do and not expensive

I’d at last drain out the Rad and replace, the coolant, there is water pump lube in the coolant that’s prob wore out. Plus a good time to clean up the overflow bottle too, I cane up,w/ a process to clean the inside nice.