Lotus Elan

Duration of antifreeze

PostPost by: William2 » Fri Feb 23, 2018 5:25 pm

I am interested to hear any thoughts on the frequency of changing antifreeze. Having had a completely rebuilt engine, new radiator and hoses, etc the antifreeze in my car looks fine after 2 years. I had filled it up using 50% antifreeze originally and made a point of using de-ionized water. I checked it recently with an antifreeze tester which showed it to be well within range and it looks totally uncontaminated to the eye. I know that the recommendation from the manufacturer's is to change it every 2 years but bearing in mind that a 50/50 mix is quite strong, I do wonder if it is really necessary to change it or get at least 3 years effective protection? I also use the car every couple of weeks throughout the UK wintertime and do about 1500 miles a year.
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PostPost by: StressCraxx » Fri Feb 23, 2018 6:28 pm

You can use coolant test strips to determine pH. They are widely available at most autoparts stores. pH should be above 7 and below 11. Below 7 is a potential issue.

If you wish, you can also pull a sample and have it sent out for analysis at Blackstone Labs. Make sure you identify the brand and type of coolant when you send in the sample.

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PostPost by: richardcox_lotus » Fri Feb 23, 2018 6:39 pm

I think the main benefit of replacing every 2 years is it gives the opportunity to back flush the system & remove any sediment.
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PostPost by: ericbushby » Fri Feb 23, 2018 7:51 pm

I don`t think the Ethylene Glycol component is going to change much in two years, unless some has been lost and replaced with water.
If there is a risk, it will be the corrosion inhibitors weakening over time due to the process of inhibiting
where dissimilar metals are concerned. We have iron, brass, copper and aluminium in the engine and radiator.
I have just replaced the thermostat and re used the drained off coolant which was clean and clear.
I now have to decide if and when to change it.
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PostPost by: AussieJohn » Fri Feb 23, 2018 9:58 pm

I was chasing an overheating problem in my tvr griffith [1994] and eventually found the rad. blocked with "white stuff" I had only covered 5,000 miles since a new rad. core and changed the coolant every 2 years [1 part coolant to 2 parts tap water] I never worked out whether it was limescale from not using deionised water or the alloy block being corroded and ending up in the rad.. Using deionised now and checking ph level [ I replaced all the hoes and removed the water pump with no sign of corrosion behind the pump but a white coating was in the hoses.]
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PostPost by: toggle45 » Sat Feb 24, 2018 9:09 pm

I had dupont antifreeze (red color) in my Elan for 45 years, most of which it was stored as a non-runner. After that time, its pH had not changed and its look and odor was original. And the when drained, the coolant passages looked clean. This was 100% antifreeze - no water mixed. Will never know if it would still have worked as coolant, but I would have bet on it.
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PostPost by: USA64 » Sun Feb 25, 2018 12:34 am

I had my Elan offline for 30 odd years and found the (Prestone?) green anti-freeze had turned into a gel at the top of the engine, outlet and heater inlet. I was glad I didn't -just get it running- as I originally planned.
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PostPost by: AHM » Sun Mar 04, 2018 11:29 pm

William2 wrote:I am interested to hear any thoughts on the frequency of changing antifreeze. Having had a completely rebuilt engine, new radiator and hoses, etc the antifreeze in my car looks fine after 2 years.

After an engine rebuild all the surfaces are clean, it will use up the corrosion inhibitors quickly! I change it after 6 months and then religiously every 2 years.

Its not expensive and it's stopping things like the water pump impeller going rusty which will kill the seal, which will then leak.

The alternative is to keep leaving it until it has a black shade... then you know its too late.

The antifreeze properties will last ages though.
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