Volvo Coolant/Antifreeze Answers

Hopefully many will read and understand the issue of using an OAT when a HOAT is needed. In the Ford motor, damage occurred quickly. This is the same reason I am always recommending a HOAT for our cars instead of an OAT like Prestone etc. If you have a turbo and you don’t use a HOAT – you are asking for it.

Let’s talk Coolant/Antifreeze… it’s important in the winter because if you screw this up your engine block will crack. But it’s also important in summer because your engine can overheat. Good news is it’s not complicated.

Firsthand Mechanic Experiences with Coolant for Volvos

Get ready for winter. If you have just water or old coolant in your Volvo, it’s time to throw that stuff out and get protected. In this Volvo Forum topic, experienced owners and a mechanic step in to guide each other — with great detail — on what coolant to use, why, and how often you should change it. Plus, novel ideas on how to flush (with water and dishwashing liquid) to get rid of deposits inside cooling components.

JimBee »

…the clerk there energetically talked me out of it. I thought people on this forum agreed it’s the best/original and should be used in the ’93 850. So I didn’t buy any until looking further into it. He said if I only want a phosphate-free antifreeze, NAPA has its own brand, but that’s not the best thing to use, either, in the 850. Part of the reason was it’s a long life coolant and leaving it in that long will cause harm to sensitive parts. He said, use the green stuff, Prestone (which by the way NAPA has on rebate special through October). So, my coolant right now is tap water and want to get some coolant in there soon. WHICH ONE SHOULD I USE?

Also, the NAPA guy did sell me some “15 minute flush/cleaner” which he said he has used for years. Is that a good thing to run in your cooling system? Or just flush it with water?

JDS60R »

After 2 flushes you will have it all out. If there is any left it will not hurt you. Just like your dishes it is meant to rinse clean the first time. If you are still nervous then do a flush and fill after a few months. Just like me you find you didn’t need it . ( But it can’t hurt and I slept better. )

Should you let it sit for a while -Oh yes – with visible deposits you need to let it run for a bit (1 hour)and then sit for a few hours. The motion of the fluid causes some light agitation and helps bring the deposits down . Sitting lets it work chemically. Be overly generous with flushing the rad. I take off both hoses and run a garden hose to it until I am sure its clean. As the water drips out the bottom you don’t have to worry about the quality (mineral deposits) in the water. I do the same for the heater core but many fear the o rings and it is still fine without it. If you are nervous you can flush with a garden hose and then flush twice with distilled. Distilled goes on sale periodically and I keep some handy. At 88 cents per gallon keeping 15 or so on hand it is an easy expense to handle. Your system will only let out 1.5 -2 gallons per drain .

If the corrosion didn’t all come out then do it again – and with a stronger mix. I put quite a bit in – probably enough to do 5 or more loads of dishes. I think I use about a quarter of a bottle. The lemon scent is nice.

The Volvo fluid has shown some silicate depletion in 3 years. It can go longer but I prefer the 3 year change. Following the 3 year rule ( was 2 years max for the old green heavy silicate fluids) I have seen many cars with 100-400K miles that have original rads and no visible corrosion. Hoses are toast every 4 years unless using Gates ECD which can go 8 years.

The low level of silicates in the Volvo fluid are repairing minor damage to your engine and rad. Over time the amount depletes (used for repair) and then you should replace the fluid mixture. No need to flush or use a cleaner . Just drain and refill every 3 years with Volvo antifreeze and distilled water.

PS- Take a gallon of your local distilled water and boil a cup of it in a pan until gone. Some distilled waters are of poor quality. You want one that leaves no visible deposits. If there are no deposits in the pan you can expect the same will be left in your cooling system. It was helpful to me to agree which pan/pot I would be using with my fiancé. I used a scratched Teflon one as its dark and the deposits show well.

On an extremely rare occasion with a horribly neglected coolant system I have seen the removal of deposits from the rad or heater core allow it to leak. Not from it being hurt by the cascade -just that it was seeping and the remove of the junk that clogged the hole allowed the leak to speed up. In these cases a core or rad was around the corner anyway.

If you want to see the effect of cascade on aluminum take a small piece and soak it in a mixture over night ( keep the metal submersed ) You will find its quite safe on the aluminum – similar to the way it cleans your aluminum pots.

This is which brand Coolant/Antifreeze to use in your Volvo