Incorrect Antifreeze - To Stick or To Change!

[riffbiker]

1996 Volvo 850 - 2.5 20v Petrol 170 BHP B5254S Engine

I have to replace the heater matrix on my car and intend to drain down the cooling system to help reduce spillage into the cabin. The antifreeze being used is Orange / Red in colour and having just spoken with the professional mechanic who filled it 9 years ago when he fitted a radiator - it is likely GM Dex-Cool OAT!!! I had no idea !!! This should never have been put in - but it was and to date does not appear to have caused problems.

So:
Radiator: 9 years old (after-market brand fitted by said mechanic)
Water Pump: 3 years old (OE Volvo)
Expansion Tank & most hoses: 3 years old (OE Volvo)
Heater Hoses - original (24 years old - appear OK and are expensive to buy)
Running Dex-Cool OAT: originally 9 years ago diluted with hard tap water by professional mechanic, with a flush and complete refill with same Dex-Cool OAT diluted with distilled water 3 years ago
New Heater Core going in imminently

I intend to drain the cooling system anyway to replace the heater core. What do you recommend, to flush and refill with Dex-Cool / OAT so as not to change and hence risk a mix of type ...

- OR flush, fill with distilled water and flushing agent and run for a few days, drain and refill with genuine Volvo V031439724 coolant (I buy at the trade counter of my Volvo dealership) which is probably HOAT ... it seems Volvo do not say what it is.

Can you recommend a suitable flushing agent if so?

Would to change now be more potentially damaging than to continue with Dex-Cool / OAT with which I am unaware of any problems - it is still relatively but not completely clean in the expansion tank after three years?

Thanks, RB

[4x4]

It was flushed 5 times in total, 3 times with Scottish tap water (if Scottish water is good enough to make the best whisky in the world it's good enough to flush my coolant system) then 2 times with de-ionised water. then filled it up with Volvo coolant 50/50 mix

[riffbiker]

Thanks 4x4! I'll run with you on the Scots Whiskey, fond of the occasional dram myself!
The tap water in my area is as hard as nails, so I would cold flush but not run on it untreated. RB

[RollingThunder]

I've read horror stories about the Dexcool stuff, I'd def flush it all out! Are you sure its Dexcool ? - some other OATS coolant is orange.

The coolant in my newly acquired S70 is of unknown brand/type but is manky brown I'll also be flushing it out when I do my timing belt/water pump/thermostat/heater matrix in the next week or so.

I'm like 4x4 - I'll reverse flush everything using a garden hose until it runs clear, do the maintenance jobs, then run it on plain water for a week before flushing it out/draining it again and refilling with 50/50 ethyene glycol antifreeze.

I'll be using Bluecol (https://www.amazon.co.uk/Bluecol-Yea.../dp/B003NVBCDM). I've used this in all my Volvos (whiteblock and redblock) for over 20+ years without any issue.

HTH

[sdg1970]

Here's a thread from a different forum that might be of interest:
https://www.cherokeesrt8.com/threads...n-my-08.91617/

I own both a 97 V70R and a 07 Jeep SRT8. Both have the cheapest OAT in them. Your call...

[Willow place]

Originally Posted by riffbiker

Thanks 4x4! I'll run with you on the Scots Whiskey, fond of the occasional dram myself!
The tap water in my area is as hard as nails, so I would cold flush but not run on it untreated. RB

The Jocks make Whisky without an "E"! , Paddy stuff use that Letter !!!

[cheshired5]

Originally Posted by riffbiker

flush, fill with distilled water and flushing agent

If there's no oil contamination, I'd steer clear of chemical flushes as 90°C water will do a good enough job of cleaning.
With no current risk of freezing, I'd fill with distilled water only and drive around as normal with a repeated drain, fill, drive around if desired and that should be enough.

After the final drain, pour in 50% of the cooling system capacity with neat Volvo coolant, top up to the max line with distilled/deionised water, drive as normal then daily check the level when cold and top up to max if necessary until the cold level remains stable at max.

[riffbiker]

@Willow Place: I stand corrected - more to the point, I never realised Scots and Irish were spelt differently. Interesting.

[riffbiker]

@Cheshired5: Thank you! Having thought about this over the weekend, I agree not to use a chemical flush - probably do more harm than good.

The OE Volvo coolant I propose to buy (#V31439724, which is actually good value at less than £15.00 / 4 litres) is ready mixed - good to go. That stated, I would advise anyone NOT to pour neat undiluted antifreeze into any engine in quantity, but to pre-dilute it to strength with distilled water. Antifreeze has a very 'searching' effect and if a system is going to develop a leak, it will after a coolant change.

[riffbiker]

@RollingThunder: Thank you! That is the problem I have. Although I myself filled the system three years ago after replacing the expansion tank and most hoses (excluding the very expensive rubber / metal heater hoses which look OK) - I do not know the exact type of antifreeze I put in it because it wasn't labelled, although I did mix it 33% with distilled water!

I know that sounds neglectfully remiss of me, but I used my professional mechanic mate's fully equipped workshop at weekends and he said to use the trade drum of antifreeze which he uses for all vehicles. That was the same antifreeze as he filled my system with 9 years ago when I paid him to fit a new radiator. It is orange and is long-life, at least 5 if not 7 years. He has shut shop now and cannot remember exactly what it was, but probably GM / Ford recommended specification OAT which could well be Dex-Cool. There wasn't the concern about it back then and it was meant to be 'the best' or he would not have used it.

The good news is that in 9 years running on it, I am not aware of any problems caused, and the coolant in the expansion tank after 3 years since the second system refill is relatively but not completely clean.

I am coming to the opinion, like those kindly commenting here, that I am better to thoroughly flush it all out several times and refill with OE Volvo coolant - that way I know what I'm running.

My concern is the possibility that IF there are remaining OAT / Dex-Cool deposits chemically bonded to the surface of the metals remaining in the system after flushing, and IF they react with the new different coolant type. I understand different types of antifreeze can result in silicone sludge which can clog the radiators.