Radiator flush @ 5 years or 150k?! Does it matter?

Not open for further replies.
Sep 23, 2014
Hello everyone, new guy here. I have a 2005 Chrysler Sebring 2.7/Touring. The coolant it uses is orange HOAT G-05. I bought it 2 months ago with 133k and I'm not sure if the coolant has EVER been changed. I tested the coolant and it's freezing point is at -33F. Would it be fine if I change it at 150k or is it "critical" that I change it a.s.a.p? I'm little worried if my car has scale/rust in the cooling system.
Last edited:
radiator flush? if by that you mean drain and refill then 60kish I guess, you mean a full coolant flush?

If a full coolant flush, I would do 150k if you used distilled water to flush multiple times(at least until the radiator is draining clear fluid after the thermostat opened up) and then use full concentrate coolant(50% of coolant capacity in the whole cooling system) to get 50/50ish.
Since I've moved away from the silicate green stuff and moved into using HOAT (for japanese imports), I never have to do any radiator chemical flush anymore. Just drain and fill with proper ratio of HOAT and off they go...good for another 5 or more years.

No radiator sludging, no rust, no nothing, absolutely amazing.

If you're worried, you have 3 options:

1) Go and get some test strips to test various aspects of coolant or send off a sample for testing.

2) Do a very thorough flush with a chemical with plenty of rinsing and then refill.

3) Do more frequent drain and fills for a while.

I suspect that option 2) is the best to make you feel more confident about this, and also probably the least expensive.
G05 isn't super long life. It's much better than conventional green, but i would flush it and get it all fresh just to have a good baseline!

I use G05 myself in my Buick.
Originally Posted By: Mter00s
that's what I meant. would using a chemical flush such as Zerex Super Flush help?

I don't see any reason for it, after the few engines rebuilds I have done, I drove the car back n forth to work(42 mile round trip) and drained the distilled water whenever I came back home, I personally did that 8 times before finally pouring full concentrate coolant in there, I just made sure to only put 50% of the cooling system capacity, this gave me 50/50 the easy way. All the subsequent top offs to the cooling system were of distilled water as the coolant quantity was already measured to exactly half.

This way all my cars got more then adequate cooling system "flush" without using any chemicals.
In Mass you shouldn't have too much lime in the tap water. In Ohio, OMG, you drink it and it tastes like alka seltzer.

If you're still on the factory fill with no top ups you shouldn't have lime scale.

Your aluminum engine shouldn't be shedding huge chunks of rust like, say, a Jeep 4.0.

I say drain and fill. You're after the additives that are going to wear out, not so much worried about freeze point, which doesn't "wear out". Testing for this takes more complicated (yet available) strips.

But on a dodge 2.7 you should keep up on all fluids. They're finicky motors.
What I did was drain the rad, filled with distilled water and prestone rad flush. Drove for a couple of days, drain and refill with distilled water only and repeated this process until the water that drained was clear. it took about 3 weeks. Then I added coolant to get 50/50 ratio as best I could. I went with all makes all models and zero problems. if I were u, I would flush it now and be done w it. Now u can enjoy your new car
Last edited:
I wouldn't use a flush chemical.

Most coolant has pH buffering additives to keep your coolant from getting acidic.

Cooling system flushes are usually acidic.

Doesn't make sense to me, to go through the trouble of keeping acid out of your system and then filling it up with acid.

I also wouldn't use soap, detergent, dishwasher tabs, or any other thing unless I had a known problem with oily stuff in my radiator. Like a transmission cooler leak or head gasket leak pushing oil into the coolant.

I'd just drain, fill, and run with distilled h2o, and repeat until what wind up with in your system is mostly clear. Then add 50%+ of the system's capacity of coolant and top off with distilled.

I'd go now vs. waiting. If you don't know when it was last done the 150k goes out the window if there were previous maintenance intervals that might have been missed. But even if 150k is the first service interval for coolant, there's two big advantages to doing it now: The weather is pleasant and you'll have piece of mind. If it's worrying you, just get it done and stop worrying.
Drain and refill your radiator with fresh fluid, and repeat every 3-4 years. I have followed this regimen and never had an issue with corrosion or scaling.
Originally Posted By: Olas
Throw a dishwasher tablet in there, drive for an hour or two then.drain, rinse and fill with tour choice of coolant

I use the cascade powder for really bad systems. Easier versus the tabs. This is an old school way of cleaning really bad systems though. Unless your cooling system is junked up I would just flush it with distilled water until it is clear and fill with the proper amount to make a 50/50
I'll probably just wait until I reach 150k then flush it until everything is clear. add a chemical flush and redo the process then finish off with 50/50 and burp the system.
The Cascade is REALLY good at getting rust out of systems. I prefer SHOUT and Mercedes Citrus cleaner, myself, but like the man says, these are acidic, and you want to flush them out of your system.

If you do use a detergent, you should disconnect your radiator hoses, heater hoses, remove thermostat, clean out each component one by one using a garden hose.

Don't worry about the distilled water until it is time to fill. If your system is that bad, its going to still be holding onto more contaminants than you will find in tap water.
The problem with old coolant is that it no longer prevents corrosion, and it can turn into sludge that clogs up cooling passages.

In fact, I deal with cars that say 5 years or 150,000 miles is good enough, but by the 4th year, the coolant is no longer any good.
Yes I think the OP should test using 2 or 3 way test strips before deciding to carry on with the coolant.
Originally Posted By: Mter00s
I'll probably just wait until I reach 150k ...

When it says 5 years or 150k miles, it means whichever comes soonest.

If you think its the original fill then it's overdue, I'd change it out now.

As mentioned above, multiple radiator drains and refills with distilled water and running it to get the thermostat open. Then drain enough of the water and replace with 100% G-05 until you reach the 50/50 mix or close enough.

Those floating bead hydrometers are useless. For $20 you can get a refractometer that accounts for temperature.
Not open for further replies.