Coolant change. - Millers57
Doing some research with regard to when to change the coolant on my Primera 2.0 SRi 1998 model (32k) I read that the concentration should be maintained at 50% & checks on the presence of corosion inhibitors being indicated by the level of alkalinity of the fluid.It gave no level of alkalinity but suggested that if was alkaline then there was no need to ghange the coolant.The alkalinity can be easily checked with litmus paper.I consulted a Nissan specialist who does most of my maintenance and he said that he checked the concentration on a service and if it was adequate he would not recommend a change.His primera has covered some 160,000 mls.
My concerns reading other posts are comments about air locks & sometimes overheating that can follow changes of coolant.Any opinions on this subject would be greatly appreciated on this my first post,
Coolant change. - Drivethru
In my Nissan Micra handbook it recommends changing the coolant every 2 years, however, with my last car, a Ford, the handbook said that as long as the correct anti-freeze was used and at the proper concentration (50%), then there was no need to change the coolant for the life of the car, which I did'nt and it never came to any harm up to 8 years old when I sold it.

I don't intend to change the coolant in this one either as my recent experience of garages is that one job causes another or at least is never done properly the first time. My motto now is 'if it ain't broke don't fix it'.
Coolant change. - Dynamic Dave
In my Nissan Micra handbook it recommends changing the
coolant every 2 years, however, with my last car, a Ford, the
handbook said that as long as the correct anti-freeze was
used and at the proper concentration (50%), then there was no
need to change the coolant for the life of the car, which I
did'nt and it never came to any harm up to 8
years old when I sold it.

The reason why you should change the coolant every 2 to 3 yrs is because the corrosion inhibiters cease to work. The coolant will still protect against freezing, but if left too long between changes, your engine will simply corrode from the inside out and eventually block up all the water ways and radiator - thus causing overheating.
Coolant change. - NormanB
You may some money on the coolant and you may even be lucky and save money on a head gasket/head if you sell the car before it/they fail!

Coolant change. - Andrew-T
As most people change cars every 2-4 years there is a good chance that the parcel can be passed before the coolant inhibitors are completely knackered. If the expansion tank is see-through the situation is pretty clear - if coolant looks like gravy, time to do something.
Coolant change. - grommitt
Be careful with coolants - the green / blue stuff is the normal coolant which it's recommended to change every couple of years to maintain the protection - the Red / Pink stuff is a long life coolant based on totally different chemistry and should last 5 years or so.
DON'T MIX THE TWO - they are not compatible and there is a possibility that the additives could react with each other and you could end up with a coolant that doesn't do what it's intended to do. Many new cars ( such as Ford ) use the new pink type.

Antifreeze performs best at 50% strength ( ie 50/50 mix) Strangely, if you use neat antifreeze, or a stronger solution than 50%, the temperature at which it freezes is actually lessened and it's ability to loose heat is also compromised. Water is the best heat exchange meduim so pure water would be best for cooling but offers little protection from freezing - Antifreeze mixture protects your engine from corroson and lowers the freezing point of the coolant whilst still maintaining efficient heat transfer properties.

Hope thats useful ?

Coolant change. - henry k
I have RTFM for Ford Focus 1999 and it says 50% coolant but
if it is the blue/green type it should be renewed after SIX years But if it is orange type it should be renewed after TEN years. No mention of how to check it apart from header tank levels. It is worth checking what is recommended for your car cos the rules certainly have changed. If the service history is suspect then the only choice is change it. Even a fancy brew is cheaper than an engine.
Coolant change. - eMBe {P}
I usually have 2 or 3 cars in my ownership concurrently. I do most service/maintenance myself. I have never ever changed the coolant on any of the cars I have owned with no noticeable ill-effect. Three of them were from owned nearly new (6 months old at purchase)to sold at 10 or 12 years. Apart from regular yearly oil changes, I change the brake fluid at 2 or 3 year intervals.
Coolant change. - DavidHM
I would guess that RTFM applies. Renault cooling systems are known for being unreliable, but the general opinion seems to be that this is caused almost exclusively by coolant not being changed. In the case of older Renaults at least, this should apparently be once every two years.
Coolant change. - Andrew-T
MB I am looking for another nice old 205 at the moment, and the ones I see (J/K/L) mostly have the gravy syndrome I mentioned before. I suspect they have been given the regular treatment you recommend, but what worries me is that judging from the depth of oil on the stick, that may have had similar treatment. Coolant every 5 years as an absolute maximum, IMHO.
Coolant change. - eMBe {P}
Andrew T - I can only go by my own experience, as a caring owner who believes in "do not fix it if it ain't broke", and who does not trust dealer mechanics to do a thorugh job. The brown gravy syndrome is something I have never come across, possible because my cars have had only "one previous owner for less than 6 months". I have never owned a French car. Just British (last 1989), or German or Japanese.

I am a Chartered Mechanical Engineer, by the way.
Coolant change. - Drivethru
Thankyou M.B. I was feeling like an outcast amongst this lot.

I have also never seen the brown gravy syndrome and never changed the anti-freeze in any of my cars with no ill effect. It's not a question of trying to save a few pounds but in my experience we are often told things are 'essential' when they are nothing of the sort.
Coolant change. - Doc
Surely it is just a case of risk.
I know a sierra owner who never changes his oil and does mostly short journies, with apparently no ill effects.
But I wouldn't take this chance.
(I change my coolant every 2-3 years.)
Coolant change. - Millers57
Thank you for the varied views on the topic but the point I wished to make initially was that the presence of corosion inhibitors can easily be checked with litmus paper (colour indicates acid to neutral to alkaline).I would imagine an acid coolant would attack the engine that is why the article I initially read said an alkaline coolant did not need changing.I am a strong advercate of regular routine maintenance such as oil changes,etc.but suspect certain items are push by the trade to generate extra business.But then maybe I am being too cynical.
Best regards,
Coolant change. - RichieW
A coolant change is is an hour job at most and one which is probably best done at home rather than at the garage. It wouldn't do any harm to consider it surely. I've been taught that you drain, refill with coolant in the correct concentration then get the engine up to temperature with the expansion cap off, this allows any airpockets to to rise to the expansion tank and escape. I think that it's worth doing at home as you won't mind the car ticking over on the drive, time pressures in the garage could possibly cause a rushed job and localised heating in the engine.

Think of the labour charges you would save although it sounds as though your local garage owner doesn't really feel that he can justify charge the labour rate on the job which is very decent of him.
Coolant change. - Andrew-T
MB and Doc - I agree in principle with what you say, but with cars, especially expensive or cherished ones, the complementary argument is "if it does break, you may not be able to fix it for a reasonable cost". Hence a sensible level of preventive maintenance.

And if your engine block is aluminium alloy, maybe alkaline coolant won't do it any good either?
Coolant change. - Onetap
This was discussed at length a couple of months back. Most anti-freeze contains glycols (except the new OAT stuff), usually mono-ethylene glycol, and occasionally mono-propylene glycol.

The problem is that the glycol will react with any oxygen dissolved in the coolant forming acidic compounds. You can?t stop the coolant absorbing oxygen, many radiator hoses are permeable to oxygen, but the rate of absorption will usually be very low.

The coolant starts off alkaline, about pH 9 or 10 I think. Once it becomes acid, below pH 7, galvanic/bi-metallic corrosion starts, attacking head gaskets, radiators or heater matrices.

The concentration of the anti-freeze in the coolant is a separate matter. It would be checked with a refractometer, but gives no indication of the level of the corrosion inhibitors remaining in the solution.

The normal recommendation is to change the coolant every 2 or 3 years and to re-fill with a mixture of anti-freeze and de-ionized water. Whilst many don?t change their coolant and suffer no ill effects, litmus paper is cheap.

Coolant change. - Millers57
Just copied this quote from my search on google:-
"Extensive testing has shown that a coolant pH below 8.3 pH is not acceptable for use in engines due to its corrosive nature. The correct pH value should be maintained between 9.5 - 10.0 pH. Below 9.0 pH it is advisable to flush the cooling system and refill with a new coolant solution".
The quote was from a supplier of hand held pH meters so they do have an interest in promoting the checking of the pH value of your coolant.In my opinion it gives you a clear indication of when the coolant should be changed.
Best regards,

Value my car