Ratling sound from engin after oil change

Sounds like valve clatter. (noise)
Check the oil and make sure it is to the correct level.
Change the oil. (and filter) If it is old, it loses its viscosity.
It becomes thin and not very effective. You may also choose to add a thicker viscosity oil to quiet things down a bit as a temporary fix. This is what dealerships do when selling a used vehicle with certain engine noises.
Be careful not to overdo it. Especially now that it is winter.
The oil will become to thick on a cold start, starving the engine for critical lubrication when it needs it most. The reason why you get valve clatter upon startup, (if that is the issue) is because the oil all drains down as the vehicle sets and it takes time to recirculate through the motor. When it is worn, nothing sticks to the surfaces it is supposed to protect.

If the oil level on the engine dipstick is correct, and you used the correct oil, then it is unlikely that you have done anything to damage you engine, however it is normal to also change the oil filer when you change the oil, did you do this. How did you check that the transmission oil was at the correct level and how did you top it up. If the oil has been regularly changed at the correct interval, and the engine has not done huge miles, then it is unlikely that you need to do an engine flush. It is easy to do yourself, as you use an engine flushing oil, run the engine for a short time, and then drain this and put regular oil back into it.

change the motor oil. but catsh the oil in a bucket orso,listen while,
the oil comes out if you dont hear any pieces falling in bucket.
second you say near trans,is it an automatic.sound can travel far.

Idont know. But u can call autozone and they will tell u over th ph.

maybe you can try doing an oil engine flush. The oil pump pickup screen might be blocked

They have been known to have pulleys lock up. Check the pulleys and the serpentine belt for tension. Good luck

Different oil brand/blend/formula? Thats a good one. As long as the oil was 5W30 it's not causing your problem. I would find a independent service center that specializes in Subaru's.

Go to autozone or similar and have vehicle scanned for codes. This will give you a idea what's wrong.

Hi Stu, A turbo only starts to help above 3000rpm. To instal a used one is questionable as they can be a real pain with internal oil leaks! Plus you will need to find an oil supply and return.
Your best bet is to give it a good cleaning an wax job, trade it in on a real 'grunter'! Frankster016

Hi

The lifters can be cleaned by getting the engine nice and hot and then adding an engine flush to the oil and leaving the engine running at a high tickover for about 15 to 20 minutes, and then giving the car an oil and filter change.

Are you sure its the tappets and not the timing chain?

Regards

Geordie