98 S70, do I need to flush my coolant if I've been topping it off with a 50/50 mix.

[ConCon]

So I've been leaking coolant for a little while and figured out my heater core is bad. I already have the parts for the heater core and am going to replace it ASAP. I went to O'Reilly's to get new coolant to top off the overflow tank because it kept getting low. (Even when it was empty I never had a problem with the car overheating). I've had to top it off 3-4 times now with a 50/50 mix from O'Reilly's. I was told it will be fine with that but I've also seen Volvo needs a specific kind like Zerex or genuine Volvo. Do I need to do a full flush and replace the coolant with something that's made for it or will it be fine. (I haven't had issues with the 50/50 mix so far)

[454cid]

Antifreeze does need to be replaced. It doesn't last forever. What you have will "work" but it's not ideal. Antifreeze controls corrosion besides preventing freezing and boiling over. The corrosion properties are what get used up.

Just topping it off for a small leak, I would have used RO filtered or distilled water.

[amblerman]

You don't specify which Oreilly's 50/50 mix you're using. The 50/50 just means it's pre diluted .

Is it the Yellow Universal 50/50 mix from Oreilly's? If it is, then that should be compatible with whatever you had in there.
If it was one of the other 50/50 mixes they have (two types of trad green and orange/DexCool) then I might want to change the whole thing.

But as @454cid says, coolant does wear out and needs to be replaced. The real answer here is "it probably depends on how old the vast majority of coolant in the car is. " What wears out is the anti corrosion inhibitors (from my understanding)

You also said "I've also seen Volvo needs a specific kind like Zerex ...."

In this case Zerex is a brand and offers many different kinds of coolant formulations.
I, and others, use Zerex G05 coolant with success although I don't think our 2000 and older cars ever actually called for that specifically.

I just looked and Zerex's G48 currently says (on the back of the jug) that it is suitable for Volvo 1991-2014 (their G40 formulation lists 2015-present).

Again, I'd be surprised if any our our owner's manuals called for the formulation by name (ie G48). It probably said Volvo coolant or equivalent . I just looked at the manual for my 1999 s70 and it only says "Volvo original coolant/anti-freeze ".

And I'd bet good money that the "Volvo original coolant/anti-freeze " they sold in 1999 is not the same formulation as "Volvo original coolant/anti-freeze " they sell today. I'd have no issues using the current Volvo coolant in my car but I'd also have no problems using G05, G48 or even some of the universal formulations they have now.

[MoVolvos]

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Scotty: "Today I going to help you answer the question, do I need to change the coolant in my car?"
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[ConCon]

It is the universal antifreeze and coolant. It's a goldfish brown bottle with a blue cap. I'm fairly certain I had the radiator flushed sometime last year with new coolant put in

[abscate]

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Scotty: "Today I going to help you answer the question, do I need to change the coolant in my car?"
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Scotty’s voice will get the corrosion of most anything.

[wahiddd]

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Scotty: "Today I going to help you answer the question, do I need to change the coolant in my car?"
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Scotty’s voice will get the corrosion of most anything.

It didn't get the corrosion out of my rusty 95' beater though

[STLV70]

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Scotty’s voice will get the corrosion of most anything.
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