Is it normal for the coolant level to decrease over driving 70k miles in 5 yrs? I'm currently at 102k, I noticed the other day that the reservoir was empty.. When I originally flushed back at 30k it was at the max line. The whole time the temperature was always the same, it never ran hotter or any different. I had it flushed finally when I noticed the reservoir, but it made me wonder if it was normal or not.

 

usually means you have a leak somewhere. prob slow. check all your hoses and make sure there are no hole or leaks at any of the fittings and check you radiator make sure there are no cracks.

 

Coolant levels are those small items that need be checked every time you change oil! If you don't have a coolant leak there's such a thing as evaporation which is probably the case after 5 years. Members on Driver should care enough about their cars so they change oil as advised and check fluid levels when doing so!
Gary

 

Hmm. I have a different problem. My coolant level never changes no matter if car hot or cold. Thought it would change some.

 

I'm gonna mark the level with a marker and put a date on it to test it out over time.

Don't ever recall seeing green spots on the floor beneath the car or any leaks from hoses, and there's the fact that the mechanic should have seen some spots or leaking during coolant flushes... So I'm sure it wasn't a leak.

 

It could be burning off instead of leaking out of the car

 

The question you really want to know the answer to should be WHEN (over the past 5 years and 70K miles) did you lose the coolant. Did it happen gradually, or was it just within the past few day or weeks? HUGE difference!

 

I have had similar issue like that before. radiator level will be ok but the reservoir was empty.

The (Nissan) dealer found a lose clam, they changed the clam and the issue seems to be fixed. but I would check on it from time to time to make sure.

 

I had that issue too after I switched to my Mishimoto radiator. Was driving around for a while like that... Turns out the cap was defective, now it adjusts slightly depending on the temperature.

 

Could there be evaporation from the cap, without obvious signs of leakage?

 

If coolant was coming out of the radiator cap you would see the dried coolant all over the radiator top surface, which is what was happening to me

 

If it was burning off, wouldn't dare be dried stains left at the source of the leak?

I'm also thinking if it was leaking into the engine, I should see blueish smoke out of the exhaust no?

 

If it has been a long slow leak that tended to evaporate in place, there is usually some residue left behind.

Coolant going through the combustion process typically comes out as a whitish smoke, whereas oil on the other hand, is bluish. Even so, if it were just a drop or two now and then, you would never even see either one. It typically has to be fairly large amount, or a constant delivery of a small amount, to manifest into a cloud of colored smoke coming out the tail pipe.

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