Hey guys!

So yesterday I did a radiator/radiator hose/thermostat swap on my 2007 4.7L V8. I drained all the old coolant out of the radiator, radiator hoses, and thermostat housing. It was a universal yellow/gold prestone that the previous owner put in.

I was however unable to drain what was left of the old coolant from the block. I didn’t even think to possibly take it somewhere and do a flush until after the fact that the job was done.

So here’s my question to you guys - how bad did I screw up? Should I take it to the dealer/shop and have a full coolant flush and refill done? Are there any home remedies I can do to fix this?

OR

Will the universal coolant that was in there mix with the Toyota Pink SLLC and I shouldn’t see any issues?

Any help will be greatly appreciated! Thank y’all for helping me with some out of control OCD.


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Unable as in couldn't reach or open the draincocks? I have an '07 V6 and while they're not easy to reach, it's possible to DIY drain the block. Surely the V8 has block drains too? If so, I would bite the bullet and do another drain and fill with the proper coolant, especially since the PO didn't have the right coolant in it for God knows how long. Others may have different opinions, I just figure Toyota has specifications for a reason.

Thanks for the reply/advice! I looked and looked and looked and couldn’t find them, nor could I find a DIY for the V8 on YT.


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The V8 has draincocks, but I've seen lots of debate as to how much it actually drains. General consensus seems to be its "mostly" drained but not completely.

OP, I'd be hesitant about mixed coolant. If the stuff that was in there is truly universal, you should be OK. I'd still get a flush kit and flush the system though.

@Napalm Go here and scroll down for the V8 drain diagram from the FSM.

Thank you guys for reply’s! I appreciate the help.

So now my question becomes - should I bother with DIY and trying to drain the block and refill it or just take it to a shop/dealer and have them perform a flush and refill it?

Also - how long is it safe to drive around like this? I probably will not be able to get it done until next week.. so maybe 100 or 200 miles, do I risk major engine damage waiting?

I have nothing objective on potential engine damage, but my subjective, FWIW opinion is there's little risk. The coolant is there to keep the engine from overheating, and it should, just like the PO's non-spec coolant did. As far as I know, and anyone knowing otherwise please chime in, the reason to use the specified coolant has to do with its formulation relative to the materials used in the engine block and cooling system components and the desired target temperature. So for example, a non-spec coolant may not have a particular additive that helps prevent corrosion in a block made of whatever material. Any issues would thus be long-term, not a couple of weeks. I can't imagine anything weird happening where the two coolants combined together sludge up or something.

To the second part of the reasoning, we don't use water any more because engines run much hotter than its boiling point and the spec coolant is designed to keep a specific engine in a specific range based on the operating parameters of that engine. So if your temp gauge stays in the green (so to speak), you're good.

With all that said, you obviously have to weigh the factors, do your own research, and make the best choice for you.

Im sure it should be fine. Prestone is a big brand that has probably done its research. But if you look on their website it says its good for small volume top-offs or a full flush. So it probably depends how much Prestone was leftover in your coolant system. If it were me I would flush it out and add the pink stuff to be on the safe side.

Drain it. Refill with tap water and bring up to temp to mix it. Drain it out including the drain cocks on the block and run water thru the heater core using one of the firewall hoses. Close up all the drains and refill with whatever you want. I like zerex Asian. Its best to not mix fluids long term. In a pinch, sure. You are fine for now, but I would replace whats in there. Aftermarket fluids are more forgiving than the toyota coolant.

Double check the drain cocks after a few days. They get corroded and sometimes dont close entirely and leak.

I've read some horror stories online about certain coolants combining and turning into a jelly like substance and clogging the cooling system thus leading to overheating, water pump failure, and crack heads.

That being said, I've never heard of this happening to anyone with a 4Runner and was curious if anyone ever had any issues mixing coolants.

I think that's the way I'm leading. Now i'm just trying to find a shop that will do it. I've spoken to several oil change places and they will do it, but the problem is is that they fill it with their own proprietary universal coolant, and I want to run Toyota SLLC Pink.

I spoke to the dealer about it, and they said they can do a radiator drain and fill, but couldn't promise me they could do a full flush and would have to wait until they had it there to see if they could. Also couldn't give me a price!

Not sure what to do!

Confidence inspiring reply from the dealer! Wonder if they can air up tires or have to check and see if have the right tools? If you don't see any problems in your overflow tank, such as weird color, particles floating around (sometimes mixing gives a particulate drop out), I wouldn't worry too much. Drain as much as you can refill with Toyota pink. Drain rad and coolant overflow tank and refill both, drive a few days and repeat and then do it again, probably take three gallons.

If you're like me, being OCD, you'll never rest and always think that maybe it's the coolant, whatever the problem is. I would bite the bullet, make an appointment with the dealership and have the system completely purged and refilled, including the overflow.

You know the color but not the chemical composition of what's in there. Just let the dealership fix it up for you.

I've never heard of issues with non OEM coolant in Toyotas, VW's and Audi's on the other hand seem to be really picky. Try and find a local shop who will do what you want. Stupid dealerships.

Not sure if you have access to the FSM but for your reference, here's exactly what it says about V8 coolant:

Engine coolant | 12.3 liters (13.0 US qts, 10.8 lmp. qts) | "Toyota Super Long Life Coolant" or similar high quality ethylene glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid organic acid technology.

On another note, and I mention it only b/c it surprised me when I was new to 4th Gens, be sure you don't have power steering fluid in the PS reservoir. 4th Gens require ATF of all things, and not even the same kind as the actual transmission takes. Again from the FSM:

Power steering fluid | (Total) 0.7 liters (0.7 US qts, 0.6 lmp.qts) | ATF DEXRON II or III

There are numerous threads on doing a PS drain and fill and my truck's steering was immediately better when I did mine.

right? I was super disappointed in their response. My dealer is usually pretty good but after that response I knew I needed to find somewhere else.

You are absolutely right. I'd rather spend $150 now and hopefully avoid problems in the future. She's got an appointment next Thursday!

That's what I ended up doing. After my dealer saying what they did, I knew I couldn't trust them with it.

Oh wow! I'll have to check this, I had no idea!!! Thanks for the advice!