1993 XJS, Six cylinders

Need an opinion on changing coolant or not changing it. I feel that it is appropriate not to change ethylene glycol based coolant if the PH is ok or made ok, rust inhibitors are added periodically and the temperature protection is correct. Agree or Disagree?

 

Coolant is technically like brake fluid: better changed every 2 years latest... Otherwise you risk deposits and corrosion in the engine.

 

There are better ways to save a little money than not changing the fluids periodically on these cars. Dump the coolant, take it to Auto Zone to re-cycle. Re-fill with 50/50 mix. I always use distilled water rather than tap although some have stated they have never had any problems with tap.

 

What you don't see is the gel and silica buildup that occurs over time. My v12 has/had heat issues (I can never tell because its a temperamental car anyway) and I've done 5 rad flushes in the space of a year each time sucking out more crap then before.

Best to flush regularly if no over heating issues are occuring, if its anything like my car get a gallon of Metal Rescue or Ford VC9 and a shop vac and prepare to spend half the day vacuuming rubber bits, sand, grey sludge and possibly dead animals out of your coolant system.

 

Brake fluid and coolant is like playing Cowboys an Eskimos. The prime reason to change brake fluid is because it absorbs moisture. Lexus recommends change every 25k miles.

Good idea to use distilled H2O. So is saving money and the fuss of draining coolant and transporting it to a parts store. Still does not answer the question "Why to change or not to change if it meets the criteria in the opening question."

Pretty red car!!! Curious, where does the gel and silica come from? I have never had a dead animal in my coolant albeit did pull out an Aardvark that was DOA. Just for arguments sake, if you have a NEW car and continue to add inhibitors and adjust the PH and insure the temperature is right do you still have to change?
As an aside I had a hot E-Type in Denver mile-high, 12 cyl and added a racing oil cooler and dropped the temperature to normal. The cooler's radiator was behind the condenser and was number three to get fresh air.

 

Lower quality coolants contain ingredients that eventually turn to gels and even a type of sand over time, I just use CAT ELC (meet or exceed EC-1 specifications) for everything I own now as it contains no superfluous garbage or ingredients that turn to gel under harsh conditions.

 

Coolant definitely breaks down over time, though more modern versions don't break down as quickly. However, they still break down. Your six cylinder engine is likely more forgiving of coolant deterioration, but there are limits.

The thing to keep in mind with extended life coolant or 'lifetime' fluids in transmissions or other components is that a lifetime is defined as the warranty period plus one day.

Do you have to change coolant every two years? No, just like you don't have to change your oil every 3,000 miles. However, would you want to buy a car from someone who didn't change the coolant or oil?

If one's plan is to run the car into the ground without regard to resale value, that makes it easy to stretch the bounds of chemistry. If you want to keep the car happy and as trouble free as possible, that's a different path. I doubt that there is a hard and fast 'right' answer, because it depends on your usage and expectations.

Cheers

 

Mac Allen, All points well taken, If coolant does break down when do you change it? Do you change it on the manufacturers recommendation or on your hydrometer reading? I would go on the hydrometer reading and not exceed the coolant life expectancy. I drive my XJS maybe 200 miles a year. With the five year coolant warranty by the manufacturer, do I change at that point (1000 miles) or go by the Hydrometer reading (Taking into consideration that the PH is correct and inhibitors added.) The reason for my question.

Looking at oil changes, since you brought it up, I think Mobil 1 gives a 15000 mile expiration, maybe 10000 miles; can't remember. In my case that would be 75 years at the 15000 mark, and I would be 164 years old!
I guess all this is academic, and boils down to a realistic maintenance plan with good judgment. Unfortunately, good judgment sometimes comes from bad experiences.

 

Water is an excellent coolant. But, and it is big one, lots of things to consider. I'll touch on only one. Some supplies are "soft" relatively free of mineral content. Not too bad to use as is with a glycol and it's additives.


But, some are "hard'. Lots of mineral content. No good.


I merely use 'distilled' from the super market, mixed 50/50 with my choice of glycol. Propolene based...


Carl

 

Carl: I think most people would agree with you that distilled water is the proper additive to antifreeze.

To get back to the question...When and why does ethylene glycol change its characteristics to no longer function as a coolant, antifreeze, and rust inhibiter or does it and if it does how is this change recognized?

 

It does.

The "when" part would vary ....which I suppose is understandable if we knew the "why" part. I don't have a tecnical explanation; I've merely accepted that coolant "wears out" eventually.



The first test is visual. If it doesn't look bright green (or blue, or red, depending on the coolant you are using) and instead has a brownish tinge, I assume it is worn out

But bright color alone doesn't positively prove anything. It must be tested. Test strips, readily available, are the most common method. Here's some quick reading

How to test for electrolysis | Vehicle Enhancement Labs


Most people don't bother with any of this and simply change the coolant on a scheduled basis. Personally, 2 years is my interval of choice.

Someone mentioned brake fluid. There are test strips for brake fluid as well although I've never used any, personally. A 2 year change interval seems appropriate although I've often changed it at two years and it still *looked* good...virtually clear....so I don't worry much if I stretch it out a bit. But, again, appearance alone is a not true test.

We all like taking good care of our cars as that's part of the "pride of ownership" thing. I include myself in this....but often wonder if I'm over-maintaining and who is truly getting the most benefit. Me, or the car?

Cheers
DD

 

Thanks Doug , a very interesting link , learn some thing new every day. I think this thread has also something to do with time and money .I also think that both your car and your self benefit from doing maintenance , better to be one step ahead and have that satisfied feeling.

 

I learned from Doug's post and the testing labs information. The three reasons to change coolant: 1. The mixture is not 50/50%, 2.The Ph is off, and 3. electrolysis is over .3 vts.
The flushing procedure is a problem because the Lab says: "Now the flush water should be flowing out of the coolant hose .... This fluid is considered toxic and should be properly disposed of." I remember when I use to backed flush my cooling systems there was copious amounts of fluid and containment would be difficult! Back then it all went down the sewer; but not now!
Good job Doug; The info was, as usual, perfect

 

Yeah, for sure those drive way flushes are a thing of the past. A good thing, I surely support that.


Carl

 

Buy waterless coolant and be done.

 

sidescrollin has a good sugestion.

i used EVANS waterless for 11 yrs in an engine, only drained it to change a water pump.

fluid was yellow color(like beer), strained it and put it back in!

it cant boil, very low prssure cap,7psi), its a vegitable base, NON poisonus, pump seal lubricant!

if you use it FOLLOW directions to the letter.

 

I have not seen it (Evans) over here in Houston. Any recommendations on where to purchase?
This is really the way I wanted to go. The thing that bothered me the most was draining and carrying pails of antifreeze to a recycler. I don't think that there is electrolysis with this product, but I am not sure.

 

Do a search on waterless coolants, the subject has been beaten to death. 99% marketing BS, 1% trying to solve nonexistent problems. You don't want them anywhere near your Jag.

 

Cooling system takes 20 quarts or 5 Gallons. Waterless coolant runs $45.00 a gallon. That's a one time cost of $225.00 a fill up. With that cost and your advise, Mikey, I think I'll stick with Prestone.

 

I have never changed coolant in a six cylinder XJS; a few questions:
Is it necessary to remove the thermostat on draining?
On refilling is there any special actions needed, such as clearing trapped air?
Any thing else?