hang on the coolant was mixing with your OIL or your transmission OIL or both?


coolant can disapear for a few reasons:-

1 leaking joint/hose/water pump/expansion tank - any of these can be hard to detect as when hot the coolanbt evaporates off - but it should leave a crystalline deposit (normall white fur)

2. Leaking radiator - external leaks ar as per 1, internal leaks can mix coolant with other oils...

3. Leaking expansion tank cap...can be VERY hard to diagnose...better just to replace in case...

4. leaking heater core...if its leaking enough wet carpets...but it really has to be leaking!

5. internal engine fault (head gasket/craked head etc) you may get steam form the exhaust (you may not!) you may get opil/coolant mixing (you may not). Cracked heads tend to open up as the engine gets really hot...and because it is hot etc you dont get noticable steam....

IF and it is IF you have 5 this might take out ANY of the other componants as the system may get hightly presurised - a GOOD mechanic can test for gasses in the coolant!

On a long run you could loose the contents of hte expansion tank to a weeping hose joint...

I would start with the easy stuff repalcethe expansion tank cap anyway, check all the hose clamps you can find for tightness (put a drive on them and try and 'snug' them)..check your carpets for dampness....clena your enigne bay top and bottonm till it sparkles, clean off any suspect crystalisation then keep an eye on it...at least if it comes backl you know its a current issue...

also check oil etc as other have mentioned for contamination...

I WOULD actiuvely persue it as it might get worse (if its a hose on its way they cna just suddenly blow out and you get VERY rapid coolant loss)...