fr1234

Driving to work yesterday, the coolant light came on in my 01 2.5td so I stopped at my nearest halfords to buy some. I've only owned the car a couple for weeks and didn't know which coolant I would need and due to the shape of the reservoir, I couldn't see what colour was already in there. The owners manual said only Ethylene glycol based coolants should be used. I asked a guy at Halfords and be confidently gave me a bottle of red, good for cars manufactured after 98. On the bottle it said "contains ethylene glycol" so I took his word, bought it and filled up.

I checked the tank this morning before my drive to check the level to see if I had a leak. The level has dropped at least a couple of cm (again due to the shape of the reservoir, you can't see more than a couple of cm deep to know exactly how low it is) and I noticed some brown sludge on the ledge inside the reservoir. (I've driven ~30 miles since putting in the coolant. Temp has remained steady just below the half mark). The engine was warm when I filled up and cold when I checked this morning.

I've checked the oil for signs of a blown head gasket but it appears fine and there is no smoke coming from the exhaust or under the bonnet.

There are no apparent leaks from anywhere.

Should I flush the coolant (if so, can someone point me to a guide to do this please)? Did I get the correct coolant? If not can someone let me know what I need please?

Any other advice for things to check for/precautions to take?

Many thanks

belvedere

You didn't say which brand/type of coolant you got, but being red, it's probably some kind of Dex-clone. Here's what I'd do: when it's cool, remove the radiator cap and fill it up. Drive it for a couple of heat/cool cycles to stabilize, then when it's cool, mark the level on your bottle. That way you can determine if it's losing coolant. If it's not, I'd thoroughly flush the system and use either a traditional green or a G-05 coolant. If it is losing coolant, troubleshoot and fix the problem, then do the flush.

fr1234

Thanks for the response. This is the coolant I used

fr1234

This is the sludgy crap on the inside of the reservoir. It doesn't feel oily

Turns out the level hasn't dropped nearly as much as I thought it had. It was quite dark this morning. When I just took these pics I could see coolant in the top of the reservoir still so it's maybe only down a cm from when I filled it.

Will do as you advise and top up and monitor this on a couple of cold to cold cycles

Thanks again

belvedere

See where it says "compatible with...OAT coolants"? OAT is organic acid technology, which is the chemistry of Dex-cool. It typically doesn't play well with other chemistries. You've only had it in for a short time, though, so just flush it well and you'll be fine.

Meech93XJ

if you want to do a good, thorough flush. here's what i do:
1.drain all coolant
2.remove thermostat
3. remove upper radiator hose where it meets the radiator
4. remove lower radiator hose where it meets the radiator
5. hook up hose to upper rad. hose and turn on.
6. flush until clear water only comes out.
7. reconnect all hoses and fill cooling system with just water.
8. turn over vehicle and drive a couple days with heat at full blast.
9. flush water out and repeat steps.
10. fill cooling system with water and prestone coolant system flush.
11. drive around with heat blasting for a day or so.
12. flush again with water.
13. replace thermostat.
14. fill to a 50/50 solution with prestone coolant.
15. seal evrything up and fill resevoir to full line.

Thats just how i did it in my old ram truck and i got it to run about 10-20 degrees cooler at full warm up temp in the summer time. for me, i was also leaking at the t-stat housing and just replaced the housing and thermostat along with the gasket because they were very inexpensive. when attaching all radiator hoses, i always put di-electic grease on contact points so that the rubber doesn't fuse to the metal.

Meech93XJ

also, dont forget to "burp" the cooling system to get the air out of the system after you do the flush.

bigbadon

OAT is fine as long as your system has NO leaks. Air will turn OAT into a corrosive mud. I don't really like OAT but if you change and flush often it is OK. The old silicate based ethylene glycol green stuff is what I prefer....However, if that stuff should happen to get into your oil your bearings will be toasted. My 2000 has the reputation for the cracked head so for that reason I only use OAT. G-05 also has silicates.

fr1234

Excellent guide. Thank you meech. I will do what you suggest this weekend. With temps here likely to drop below zero over night are there any issues involved in having it full of just water?

Meech93XJ

Yes, that is a MAJOR problem. The water will freeze and crack your block. Do not allow it to freeze. I did that whole procedure in the summer time. Sorry I forgot it was winter

fr1234

Ha. No problem and thank you again.

I assume burping the system will just involve letting the car idle with the radiator and reservoir caps off until it reaches normal running temp? (And then topping up when needed)

Firestorm500

Hmmmm. Never heard that before. Maybe that's why GM uses DexCool in the head gasket blowing-prone Northstars.

bigbadon

Yup, I had 2 chevys that suffered the OAT (Dexcool) woes. Once that stuff changes its chemical composition it will eat through gaskets, including head gaskets. It ate pinholes in the metal gooseneck for the upper radiator hose on my Blazer. I might switch over to the old green stuff on my next flush. The one good thing about silicates is that is an effective stop leak and is one of the reasons it was put into antifreeze. The OAT and G-05 have an organic type of stop leak/lubricant. In a completely closed system (not an overflow bottle) OAT is fine and that is what the new GM cars have gone to.