On Monday I got an oil change and I topped off the coolant in the resoirvoir, now 3 days later the level is about an an inch to an inch and a half below the max line, I drove a total of maybe 150 miles and total time maybe 5-6 hours how the heck did it go down like that?

 

Cold and Hot engine temps will make the level vary.

Check it the same time every time, ie - first thing in the AM cold engine before you start her up for the first time.

 

After doing some repair work our SE was running on plain water for months. Then the day after I flushed and refilled the radiator with coolant, I noticed that the car had a coolant leak. Turned out to be a bad water pump....I suppose the coolant cleaned out some rust that was plugging the leak or something . Check for leaks.

 

Fill it again and it should be fine (unless you have an obvious pool of coolant under your car). I think it takes a while for the coolant to go along that thin tube into the rad. The same happened to me 4 weeks ago after a coolant flush, and after I topped it up the second time it's been solidly on the max line for two weeks.

 

After a coolant flush you may notice this for a while. If you've not flushed it in a while and you'er checking at the same time everyday and it's going low, then you have a leak, or worse something sending that coolant into the engine. The latter possibility is unlikely. A simple leak is not a huge dael, though it should be fixed.

 

You may have a water pump leak. I had the same issues and thats what it was. Best way to know if its a leak is to keep driving regularly while paying close attention to the temp. guage. If the engine temp starts to climb above normal (indicating no coolant) than you know you have a leak.

 

No no leaks and the engine temp. gauge is always in the middle so I'm assuming the level just varies with the temp. gauge.

 

Well refill it to the max line again. Probably after the flush you needed a little more fluid than normal. If it goes down again after the refill than you definitely have some kind of leak somewhere. If your temp stays normal than its really not a prob unless your temp guage/sensor is malfunctioning.

 

Yesterday when I had checked it the level was where it was at after the car had been sitting for approx. 4 hours or so. This afternoon when I checked it the car had been sitting overnight and the coolant level was the same as it was yesterday, no visible leaks, puddles etc., so I'm assuming the coolant level varies with the engine temp.