My TJ is due for a coolant change as it has been 2 years since the last time. I'm going to use the genuine coolant. Can I just drain 5 litres from the radiator drain then top up with 5 litres of new coolant, this is what the dealers do and they claim that it is enough to keep the coolant fresh.

I know that the complete system holds 9.5L. Last time I removed the cylinder block drain plugs and flushed it out with the hose, then filled it with the premix coolant. This is time consuming and also requires 2 bottles of the coolant at aprox $100.

I'd drain the whole lot and use a concentrated coolant and distilled water. Nulon make one I believe.
Should cost less than $100 easily.

http://www.nulon.com.au/products/Cooling_Systems/Long_Life_Concentrated_Coolant/#.UodZQlyR1w0

Makes 15L in total. Life of 4 years/250,000 km. $40 at Supercheap.

The drain plugs are not too hard to get to on the 3rd gens so this enables you to do a proper flush. Not so easy on the 380 - I could only get to one of the plugs as a DIYer at home. Ramps or car stands are needed though.

In Vic no need to use any distilled water. Using genuine coolant is a waste of money as is 66% water anyway

Drain the whole lot, use Nulon Green about 2.5l to fill, you will not get the complete amount out as there are spots where even once both block plugs are out coolant will still remain.

Where are the block drain plugs for the 3rd gens?

One is on the rear of the block near the transmission end, other is front sort of behind the dip stick, just near the bracket which holds the dipstick tube onto the block. Both are difficult to access and can be very tight.

Are they plastic or metal plugs?

Metal, 14mm heads

380 has them in the same place, some of the later 380 have a hex 10mm allen key style on the rear bank

Thanks mal.

Mal,
My pm's arent working

Do you have a 2nd gen electric antenna and lh rear tail light assy available

I went to the Mitsubishi dealer's parts department today to get some coolant. Spoke with the guy there and he said that changing 5L is fine as all they do when servicing a car is drain the radiator which he reckons removes about 3L. The current genuine coolant must be good for longer than the 2 years the service book says if changing only a third of it keeps it in good nick.

The current genuine coolant must be good for longer than the 2 years the service book says if changing only a third of it keeps it in good nick.

Yeah, must be good . . . /sarcasm tone ON

How do you decide if the coolant is in "good nick" though? Do the Mitsu service people assume it is ok? Or do they have equipment to actually test the "refreshed" coolant?

(I think I know the answer . . .)

If a backyarder changed your coolant like that, you'd be jumping up and down with indignation. 3L fresh onto 6L old gives you 66% old - hardly a "good" coolant change.

A few of the dealers I've spoken with do it this way, so I'm assuming Mitsubishi have done tests and told them to do it this way. Either that or they're all dodgy. I had my car serviced by a dealer once and 2 years after I tested the coolant with a Castrol test strip and it came up as OK for corrision protection and antiboil protection.

Yes, I have the test strips too. Why not change the coolant completely, and use the test strips to tell you when it needs changing? If the coolant is that good, perhaps five years before the pH goes into the danger zone?

I went to the Mitsubishi dealer's parts department today to get some coolant. Spoke with the guy there and he said that changing 5L is fine as all they do when servicing a car is drain the radiator which he reckons removes about 3L. The current genuine coolant must be good for longer than the 2 years the service book says if changing only a third of it keeps it in good nick.

And dealerships change 5l of auto fluid, charge you for a flush and tell you its ok. Add to this they also change a timing belt, leave the seals and pulleys and tell you this is ok as well

Is frustrating when everyone on the forum including those of us with experience give advice and it goes totally ignored. Why ask if you are going to just go and do your own thing

Paying $45 odd bucks for a 5l bottle which is 4l of water is insane. If you have now purchased it just do what the dealer states as it seems the guy at the spare parts counter (who clearly is too skilled to be in a workshop) must be right.

If not do what the rest of us have suggested, save yourself some $$ and do the job properly. There is nothing wrong with the Mits coolant aside from the massively excessive price and the fact it is mostly water.

Perhaps service centers no longer take the Magna (or 380) seriously? It is a "minimise time and materials and maximise income" type of situation for them?

Anyhow . . .

I'm surprised no one has mentioned the overflow bottle. I change coolant every 2 years, and flush out the coolant bottle. Surprising amount of muck comes out, the coolant is a much darker and murkier colour, not clear and light green at all, and at times sheets of slimy gray stuff comes out. Apparently some organic coolants are a good breeding ground for air borne yeasts. Breed nicely in the warmish overflow bottle, will get killed when the muck in the overflow bottle gets sucked back in as the engine cools. But honestly, do you want that muck sucked back into the radiator?

I bet the lad behind the parts counter didn't mention that. lol

TL;DR

When doing a coolant change, flush out the overflow bottle too.