Bits and Bobs.

[steelcityuk]

Hi All,

In a fit of celebration (the sun finally appeared), I decided it was time to change the anti-freeze and the gearbox oil. Both have been in for about a year but the anti freeze was cheapo stuff and the gearbox oil not strickly to spec...

The XM hasn't lost any coolant so I treated her to some lovely lime green anti freeze that I picked up at Costco whilst it was on offer - Prestone extended life antifreeze. The cheap stuff that came out was a bit cloudy but still blue coloured. The gearbox oil was Q8 but has now ended up with semi synth from GSF.



Another trip to Luton is on the cards so that'll be another 300 miles on the clock.

Steve.

[White Exec]

Hi Steve,

Just remember - DO NOT mix antifreeze/coolant types (i.e. don't mix long-life OAT (organic acid technology) types with standard stuff). Results can be dire: blockage, crystallization, goo, etc. etc. See write-ups elsewhere.

If changing antifreeze/coolant, be sure to flush out ALL previous mix. Top-up with identical mix ONLY. Take no notice of fluid colours: they mean nothing at all.

Personally, I'd recommend Citroen's own (Dynagel 9103) - it's not expensive.

This is heartfelt advice.

Chris

[steelcityuk]

Hi Chris,

I did give her a flush out just to be sure but the Prestone is OK to use with any existing antifreeze.
http://www.shamrockchicago.com/PrestonAf.html

The Prius is next on the list for it's coolant changing. I like their de-icer too - Prestone that is.

The gearbox oil was a bit dirty but draining it into a non clean tray made it look terrible, is it really that good at dissolving grime?


Steve.

[kenhall]

My gearbox oil looks like that but that's because I add Molyslip (which is rather black)!

Ken

[White Exec]

Hi Steve,

I've read through the Prestone product description attached, and it confirms that it is a long-life O.A.T. product.

As such, we should NOT MIX IT WITH ANY STANDARD ANTIFREEZE/COOLANT. The two chemistries are just not compatible, and can produce sedimentation, crystallization, sludge or goo, depending on what it's mixed with. There are numerous internet sites which describe this.

Prestone claim their product is compatible with any vehicle, and any colour of coolant mix. OK, I'm sure it is. But this doesn't say anything about mixing it with other antifreeze TYPES, except to hint at a reduction in its normal 'long life' if mixed with other products.

If changing coolant, remove ALL the previous brew, and use ONLY one mix for refilling and topping up. This looks like what you have done, so everything should be fine.

Chris

[addo]

I'm yet to see myself, the dire results threatened, of mixing coolants. Accordingly, I am very cynical about this risk.

I've spent enough time in a workshop environment abusing tools on a variety of cars to see many outcomes of ill-considered choices. Nor have I seen similar findings posted with absolute certainty, by anyone I "know" well enough to trust.

Until then, it stays - for me - in the Chicken Little category, along with not mixing LHM and Mormons.

[White Exec]

Hi Addo,

I was sceptical too, until I inadvertently mixed standard type with long-life O.A.T. (organic acid technology) type. The result was a thick grey goo, forming on the surface of the coolant in the expansion tank, where there is contact with air. Remove the goo, and it reforms, again and again.

The results of this accidental mixing of types has had extensive write-ups, but don't take it from me . . . but try this link for an authoritative warning:

http://www.bluecol.co.uk/index.cfm?page=75

Don't however, take any notice of the colour of a coolant/antifreeze mix: the use of colours is a completely arbitrary matter, and varies between one manufacturer and another. There is no accepted standard.

The origins of long-life OAT-type mix lie partly in a requirement by vehicle manufacturers for a coolant mix that would be effective for a number of years, to get them through (a) new vehicles being layed-up in storage for lengthy periods before first delivery, and (b) the need for the vehicle supplier to have to drain and replace the coolant at the time of sale, or shortly afterwards.

Chris

[addo]

What you were observing, was possibly soluble oils in a traditional coolant base being brought up and emulsified by the active ingredients in OAT coolant. Not ideal but probably fairly harmless.

Excluding water, the added in item I've seen do most damage in cooling systems, has been "stop leak" additives. Used to excess these can readily block a ¾" ID hose. The most damaging engine detail in quite a few motors - including the PRV - is a block mounted oil cooler that corrodes to let oil into the coolant.

Most cars seem to get scrapped from accident damage, free market worthlessness, or (in the UK) gross structural corrosion. Seems to make a steady supply of engines available, if people push the boundaries of casual maintenance too far.

[White Exec]

" What you were observing, was possibly soluble oils in a traditional coolant base being brought up and emulsified by the active ingredients in OAT coolant. Not ideal but probably fairly harmless. "

Hi Addo,

Interesting.

This was the contents of my coolant expansion tank after unintentionally mixing the two types of antifreeze. After a couple of hours on the road, the tank was two-thirds full of the grey-black stuff. It had the thickness of clear honey, was immensely sticky, and wasn't water soluble at any temperature. It was only possible to remove it from a surface (where it adhered) with strong detergent and hot water. Available solvents (petrol, alcohol, kerosene...) would also not shift it. The goo was, mercifully, only in the expansion tank, and I had to remove the tank to clean it out. Below the goo was decent, clean, fresh coolant mix, not discoloured.

Thinking I had removed it all, I refitted the tank, and topped up (mistake!). Within a short driving time, the goo had re-appeared, in the same quantity.

I read up extensively on the web, and found large numbers of reports of everything I've described. Some sites commented that the goo forms only where there is air-contact with the contaminated coolant - i.e. in the header tank. In a system that has not been properly bled of air, this formation could, presumably, occur in air pockets anywhere in the system, which doesn't bear thinking about.

The cure was to completely drain the system, thoroughly flush it with a system cleaner (I used Liqui-Moly Radiator Cleaner #2506), and refill with a known and single mix (Citroen Dynagel). Since then, the problem has never resurfaced.

Altogether a nasty experience, definitely "not ideal" and certainly not "harmless" !

Chris

[addo]

If it were indeed not soluble by either polar or non-polar solvents, then one could reasonably surmise it to be polymerisation. That would be hellishly obscure (and I think unlikely).