Suzuki Club UK

Hi guys - very new here and also very new to Sam my 2005 Grand Vitara 1.6
I bought Sam a month ago and have had the timing belt and water pump changed, also had an oil change done on him, he wasn't pulling well and have had the lambda sensor changed as well.
I have noticed (I think he was doing this before the work done) that he uses water. I have no leaks, no condensation (that I have seen) from the exhaust, the oil isn't milky, and the radiator is not using water just the expansion tank, he also doesn't run hot, gets to his normal temp and stays there. I have checked and only fill the reservoir to the max line and have lined up the little arrows when refitting the cap.
He also runs a little like a diesel and was wondering if it is the head gasket on the way out, although I have none of the normal symptoms?
I have already spent a fair chunk of money on him and don't want to get the head gasket done in case it isn't that - I have been told it could just be a faulty thermostat, or even the cap for the expansion tank.
If you guys could give me any ideas to try first before handing over a large sum of money to my local garage it would be really appreciated.
Thanks guys

Hey Bobby,

My vitara had a leak on the heater matrix cab side of the bulkhead which ran out down the bulkhead and was hard to find. pressure test your system if you have the gear. a garage can do this for you for minimal cost. i used to charge £10 to pressure test. What your looking for is a constant pressure if it drops you have a leak.

You then just have to find it

Might be worth sticking a new rad cap on just to make sure its not that.... should only cost a few quid and wont hurt