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Rapid sound Tic Tok at start

I have a 1998 Subaru Impreza outback sport with 2.2l engine and 115000 miles. A few months ago I started to hear a Rapid sound Tic Tok at start; It’s a lightsound. It would usually go away after the car is warmed up. I heard it the most when my engine was oil was low but I filled it up and it mostly went away although I still hear it when I first start. Is this engine knocking or pinging? and is it a problem if it goes away after the car warms up.

If it goes away after the engine warms up, it could be piston slap, which was characteristic of some Subaru engines of that vintage. Piston slap is more annoying than anything, and ultimately is not dangerous. However, you also stated that you heard the noise most “when the engine was low on oil”.

If you chronically ran the engine when it was low on oil, then there is also the possibility that you caused bearing damage. How low is low, how far did you drive each time before you replenished the oil, and how often did this type of situation occur?

Half way on the dip stick is how low… and that’s the lowest. I started the car today and the sound was gone after a minute.

It’s not knock or ping, which occur while driving with the engine under load.

The 2.2 has hydraulic valve lash adjusters, or lifters, and if one is a bit sticky it will “click and clack,” until it warms up.

Another possibility is the infamous Subaru piston slap, as VDCdriver said.

All things considered, I don’t think it’s anything to worry about. My 2.2, with mileage similar to yours, occasionally taps a bit on cold start, too.

Halfway down the dipstick is not low oil. Are you using 5W30, or something else?

Thankyou! I’m currently using 10w30

I would guess it needs an oil change. it’s probably a valve lifter dirty and/or sticking.