If you run it for very short trips or just for warm up, you're doing more harm than good.

Oil needs to be warm and circulating to properly do its job of protecting your engine components by lubricating the parts and cooling them. Oil is the lifeblood of your car. If you run it for warm up lang and it reaches operating temp, then you shut it off once it does, it's like teasing the car into saying you'll drive it but you'll spoil the fun by cutting it short.

Cars love to be driven, to drive them on a daily basis will exercise it and remove carbon deposits (assuming you drive a healthy run). The reason that you're doing more harm to warm it up and shutting it down right after is because like I said oil must be warm and circulating for long periods to effectively do its job. If it does not do this, then it cannot protect the engine as best as it was designed to do such as when warming it up for a few minutes and shutting it off even if the engine hasn't reached operating temp. Take it for a spin, give it a good blast down the highway, and it will reward you plentiful.

Give us a good estimate of how long it's been since you've changed its oil, then we can give you a definite answer. What may be a long time for others isn't so with some, so subjectivity comes into the picture. It is also recommended to change the oil at specific mileage intervals or time intervals, whichever comes first. Why don't you use it more often for a change? That way hindi siya nabubulok sa garage niyo.