Can I just add more coolant to my car?

Posted by ISmokeEther@reddit | askcarguys | View on Reddit | 22 comments

The coolant is well under the cold fill line and it's been nearly 5 years and 50k miles since I got the car, should I get a full flush or can I just add more coolant to the system?

[-]

ISmokeEther@reddit (OP)

17 GMC terrain with the v6. The current mileage is about 79500

[-]

MarcusAurelius0@reddit

Recommended flush and refill is 8 years or 90k miles.

Time for a full drain and fill at least IMO.

Wouldn't trust anywhere but a dealer or brand knowledgeable mechanic to do a flush and refill.

[-]

Cute-Crab8092@reddit

You wouldn’t trust anyone but the dealer to pull the plug on your radiator and refill it ?

[-]

MarcusAurelius0@reddit

To flush it, drain and refill is different than flush and refill.

[-]

SolarE46@reddit

Yes and no, Id just run a hose through the thing for the rad, then close it, run it, open it easy Bing bam boom it’s flushed

[-]

MarcusAurelius0@reddit

Flushing is usually done with a chemical cleaner.

I'd put running a hose to clean out the system as the same as a drain and fill. You're just forcing all the coolant out of a system, not actually cleaning it.

[-]

S7alker@reddit

Depends on shop and machine. My old shop we didn’t use a chemical, we hooked it up to a flush machine to cycle out the old coolant.

[-]

Yeah the “chemical cleaner” is distilled water lol. When I flush I fill it with hose water and run the car then drain it like two or three times, afterwards I do the same thing except with distilled water and then fill with coolant. You wouldn’t believe the crap that comes out after a few flushes on older cars

[-]

Useful-account1@reddit

It’s recommended to flush the coolant every 8 years in those cars, so it’s about time. Take it to a reputable independent shop, it shouldn’t cost too much. The coolant is likely looking low just due to evaporation over time, or air in the system.

[-]

DetectiveNarrow@reddit

Just add it. ,check again in a few weeks and if it’s low again take it to a shop. Coolant doesn’t burn but it’s normal to need to top up every now and again

[-]

Another_Slut_Dragon@reddit

If you are due for a flush, just top it up with water for now. If you have hard water, use bottled water. If your area doesn't stain the toilet bowl with hard water tap water is fine.

[-]

Elitepikachu@reddit

Tap water or pure water are never an acceptable option for filling a coolest system. You have no idea what you are talking about.

[-]

Another_Slut_Dragon@reddit

Hard water and mineral deposits are the problem and it entirely depends on local water chemistry.

Funny enough, I now work with industrial RO filtration equipment capable of doing 80,000 a day. I have intimate knowledge of water chemistry.

Here in the lower mainland of BC it is a rain forest and we have low TDS (total dissolved solids) in our water. Run it without issue. One of my customers runs a million BTU boiler on straight tap water because there is a risk of a heat exchanger crack contaminating wash water in a food plant. The boiler is 25 years old and breezes past any inspection. Try that in an area like Calgary with their hard water and forget it.

[-]

jasonsong86@reddit

Just top it up if coolant is in good shape

[-]

rickybobbyscrewchief@reddit

In theory, coolant systems are sealed/closed loop. So low coolant is probably a sign of a leak. How big the leak is depends on how fast you're losing it. However, in reality, the system has a couple places that you can have slight losses under normal conditions. So being low after a number of years, isn't all THAT concerning. You could definitely just top it off and keep an eye on it to see if it drops back down within a few weeks or not for well over a year+. If it drops fairly soon, then you do have something leaking slightly. If not, nothing to really be too concerned about if all you have to do is top it off once a year or so. Just be sure to top it off with the correct type/color for your particular make and model. When I was young, I made the mistake of mixing coolants and it was not pretty (although a full flush and new fluid kept her going for many years, so nothing permanent).

I believe GMC says 5 years or 150k miles on fluid flush. The 150k mile thing is a bit of a stretch, IMO. But 5 years is probably fairly reasonable. So being at 5 years, and knowing you *may* have some little leak going on, it wouldn't hurt to just go ahead with a full fluid change. Get that level set correctly with fresh new fluid and then keep an eye on the overall coolant system for any signs of a further developing issue.

[-]

Jandp1@reddit

I would definitely drain it. Put in a radiator flush, then drain that. Then fill with new antifreeze fluid. If you have to mix it with water you should use distilled water to keep the impurities out.

[-]

TheWhogg@reddit

You can just add. Do you know when coolant was last done? BMW recommends either every 2 years, or never (depending who they are talking to). I think 5 years is long enough for any fluid and would change it.

Some say you need to investigate for a leak. Personally I’m unsurprised by fluid at 105C or so boiling off gradually so would not panic about fluid level decline in 5 years.

[-]