Morning clatter



I get a lot of engine clatter when I start up each morning. After the engine warms, the noise subsides. This is a 4-cyl engine. Should I add something like STP to smooth-out the startup? The car is a 2004 and has low mileage (<40k)


STP will probably INCREASE the noise.


Well, OK no STP. Anything else you can suggest to get rid of the clatter? Or, is this just the nature of 4-cyl Forester?



What kind of oil filter does it have?
A major brand or a cheap generic job they put on at quickie oil change joints?


Just so that we can rule out poor maintenance and the sludging that results from poor maintenance, please tell us how often you have the oil changed.

By my calculations, you put only about 8k miles a year on this vehicle. If you are waiting until 7,500 miles to change the oil, that is not sufficient. For a car that is driven as little as yours is, the oil needs to be changed twice a year at the minimum.

How often is your oil changed in terms of both odometer mileage and in terms of elapsed time?


My 04 Subaru WRX clatters for the first min or so when cold but not really loud but you can hear it. It has a smaller 2.0L turbo motor instead of 2.5L motor.


Is the filter accessed from under the car or from the top? If it is from the top, it likely should have a anti-drain back valve in the filter. Cheap filters sometimes don’t have the valve or it fails to function. If that is the problem replacing the filter will with a proper one will correct the problem after one startup and drive cycle.




You have to determine what the cause is…It could be oil not getting to the heads fast enough…could be an exhaust manifold gasket leak. If it’s oil then make sure you’re using the proper oil and filter for this car. If you are then try an engine flush or Rislone to see if that solves the problem.


Sounds like piston slap to me.
A common problem on some Subaru engines for a while.

Aside from a complete rebuild, there’s nothing to do or worry about.



Yes, it could be piston slap.
It could also be poor oil circulation as a result of sludging.
The OP has still not answered my question regarding how often the oil is changed.


The problem is the timing belt tensioner. have that checked out.