I’m due to drain flush and refill the coolant in my Mk1. Having scoured the forums and internet in general, I’m still left looking for a short and conclusive answer to a coolant question:
Is Silicate a good or bad thing to have in my new Mk1 Coolant?
There are loads of coolants out there to choose from, all Ethylene Glycol based (which is what the sticker on the under the bonnet recommends), but some are silicate based, some silicate free, OAT, HOAT, NAP free etc etc.
From my research there seemed to be benefits from the OAT/HOAT longer life type coolants, but lots of suggestions that they are not ideal for Mk1 MX5s. Older cars seemed to run with silicate based coolants but lots of suggestions that Japanese engines shouldn’t use them.
Lots of recommendations for a Mazda Green coolant for MK1s (not the FL22 long life stuff), but from what I can see that includes silicates, so no different to lots of other silicate-based coolants out there.
So, the question seems to boil down to - silicates or no silicates for a Mk1 MX5 Coolant?
We use and recommend Mazda’s own mix or Texaco’s, but you must also take into account if you have silicon hoses fitted or standard OEM hoses, as some coolants can react to silicon hoses, so please check.
Regardless of which every collant you do go for , It is always highly recommended to flush and back flush the system when changing to fresh coolant/antifreeze .
M-m
Thanks for the info MM. All OEM hoses, inc the new heater hoses I’ll be fitting; and I will be giving the system a thorough flush before filling with new stuff,
I’d heard about the Mazda long life FL22 fluid being backward compatible and rang two Mazda dealers to enquire what they recommended / sold.
Both Mazda dealers said the new stuff (FL22) can only be used in newer cars, and that they don’t sell anything suitable for a Mk1 MX5.
They both advised similarly, ‘just buy some of the old stuff from a motor factors’. When asked what constitutes the old stuff one said anything green with ethylene glycol in it, the other said old blue stuff like bluecol (which is silicate based).
I know I probably can’t go far wrong whatever I put in as long as the old stuff is properly flushed out. Just thought it would be nice to get a clear steer on what type of coolant was best suited to a MK1. Choice seems to be: new organic 5 year stuff, old school silicate 2 year stuff, or a hybrid with both, all of which are available from various manufacturers.
Yeah sounds about right for a dealership, what department did you deal with on both ? so they really have recommended " use any old cr*p" off the shelf, oh to have their knowledge.
Texaco do a good five year one, mix it with deionised water 50/50 mix and sorted
But on a foot note , the chaps at the dealerships are talking rubbish, our local one sell the ready mixed in 5ltrs, and I buy it from them to use on regular occasions , which i am just about to get two more tubs today from them to go in a mk1, but we have a very good lady on the parts desk here that as all the part numbers in her head, which makes it all simple ,easy and a pleasure to deal with.
Thanks for the replies and comments on this coolant query.
As local Mazda dealers weren’t of much use in recommending a specific coolant for a Mk1, I decided to contact Mazda UK. After a couple of emails requesting further details of my car (down to VIN), and confirming that I would be flushing out the old before refilling with new, this was their recommendation:
Thank you for contacting Mazda Motors UK.
*I have raised this query with our in-house Mazda Technical Specialists. They have advised as the system is due to have the cooling system flushed, we would recommend FL22 gold coolant issued. This coolant is a mixed coolant available from any Mazda dealer and was designed to be compatible with all older generation Mazda cars and is a long-life coolant. *
From what I’ve read, FL22 gold coolant is an Ethylene Glycol based coolant with OAT anti corrosion additives and is silicate free.
So, based on that (and a recommendation from Mazda Mender) I’ll be trying round local Mazda dealers for best price FL22 gold.
Picked up a 5l bottle of FL22 Gold premixed coolant from Mazda Dealer in Preston for £14.80. A couple of others I tried only had concentrate at £50 for 5l. Also picked up some de-ionised water (not from Mazda) for flushing system.
Looked under front of car to identify best tool to remove plastic drain plug to find it had previously been damaged. At this stage got straight onto Autolink and ordered a new one (which arrived next day).
Gave it a gentle go with best fitting screwdriver I had but it just crumbled. Mazda Mender site recommended heating the end of a flat blade screwdriver and melting a new groove into the plug, which was a good tip, but unfortunately didn’t work for me, probably because there wasn’t much left of the inner of the plug.
It looked like I needed to get a fine deep groove across the outer edges of the plug which were still intact in order to get some proper turning force.
I cut a small flat piece of metal to make a key just the right width for the plastic plug and attached it to the end of my soldering iron, and when hot very carefully melted a deep groove across it edge to edge (being very careful not to damage the drain port on the radiator). When cooled the metal key was a perfect tight fit in the groove in the plug, and out it came.
After numerous flushes, removing and cleaning out the expansion tank and filling with new coolant the new plug was fitted (very carefully) - job done.
The reason the plastic drain plugs snap are because of them being fitted dry and over tightened from people worried it will leak from there , so it must be as tight as the crank bolt, which i understand but all the info is out there to help stop or rectify these issues then with heat they dry and stick, someone comes along and then tried to remove the jammed plug resulting in either chewing up the plastic phillips head or snapping as in your case, we deal with it a lot, hence the quick vid we did to show what to do, a smear of red rubber grease on the thread and sealing O ring on refitting stops if from sticking , helps with the better seal and deterioration for next time its time to attack.
M-m
I’m glad I found this article, as I want to flush out and change the coolant on my 1993 Eunos 1.6. My local Mazda parts guy has never heard of FL22 Gold, but I found it online.