like title says, my radiator has a DO NOT ADD COOLANT sticker and I want to know why I shouldnt, like, the science behind it and all.
pretty sure my radiator is aluminium, and im wondering if anyone added coolant in their alu radiator also and how did it turn out

ps: i bought 3 liters of toyota long life coolant without seeing the sticker, nice.

I use Koyorad aftermarket full aluminum radiator and coolant all.this while, no issues whatsoever.

DO NOT ADD OR DO NOT MIX?!?

Most sticker i seen is do not MIX with other coolant as some coolant when mix (Example original Blue mix with red or green coolant) can come out even worse effect like become sludge/slimy water which may even worsen the cooling system.

The best is to use back the original coolant from the manufacturer. If your ride is not Toyota, do not think- that all other rides is compatible with it especially with newer full aluminum engine their coolant already using blue or pink color type.

This post has been edited by littlefire: Mar 9 2022, 11:10 AM

Encountered this before, hence the answer as below.

The "Do Not Add Coolant"sticker would be from 3rd party radiator, i.e not original or replacement part. The material may not be as good as the original, hence to avoid acidic corrosion from prolonged non changing of coolant, the non original radiator manufacturer are against it.

Long life coolant (must mix with water) is recommended to change every 2 to 3 years, if not, it will become acidic. Super long life coolant (ready mix) lasts 8 to 10 years.All Toyota cars from 2010 are using Super LLC as standard from factory.

This post has been edited by mot88: Mar 9 2022, 05:04 PM

Even APM original also have that sticker

APM aftermarket radiator sticker usually is Do Not Mix Coolant, Do not Mix & Do not Add is totally different meaning.

Previously a lot of people think is no need add coolant then got 1 spare part salesman ask me you use google translate or dictionary what is the meaning between Mix or Add? Basic understanding of the words first, some so call radiator expert in the net say no need add but you will spend more time & money every year to service in his shop if turn into full rust water.

A lot of CKD cars like Nissan & Subaru Xv in Malaysia also using APM radiators with original manufacturer coolant filled in when new, so i believe the warning is more towards mixing other coolant together.

This post has been edited by littlefire: Mar 11 2022, 10:32 AM

Mana tau la , for me do not mix coolant is saying do not mix in coolant with the water , just plain water.

Because you add water to a radiator you don't add petrol or diesel , but water can mix with coolant , so don't mix coolant means just straight water.

If they said do not mix old coolant or fresh coolant only or flush old coolant before use then clear.

Newer modern cars no add water already, mostly just pre-mix coolant. (Some cars manual even state do not add water but pre-mix coolant)
There are a lot of different coolant outside selling, the main reason is not to mix different brand or type together unless you know it is from same source.
It is good practice to flush the old coolant before use, but if emergency try to use back the same coolant.

This post has been edited by littlefire: Mar 11 2022, 03:06 PM

Initially, I was thinking the same thing as you. However, there really are written on some radiators that "Do no add coolant". I also find it to be unbelievable. Most probably it's typo and wrong translation. You know lah..those China made products or fake products.

Personally, there are no problem using coolant on aluminium radiators. Just don't mix them and be sure to change every 2-3 years.