Oil light still on after oil change.

don't trust any people for engine oil change take oil level after they change it.

Really don't know what he was doing? But it sounds like you need to reset your ecm, "Computer"
You may need to call the dealer on your make of vechile and ask how you do this, But this is for sure where i would start. Good luck and allways get a sec. opinion on major work,

you need to reset the maintenance reminder

This fix works for 2.7L engine. Worth having your mechanic look at.

Answer
NO: 08-36-99
SUBJECT: Engine Oil Pressure Light Flicker
DATE: Oct. 15, 1999
OVERVIEW:
This bulletin involves adding a terminal/wire/vent to the oil pressure switch connector.

NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 2.7L ENGINE.

SYMPTOM/CONDITION:
With a hot engine the oil pressure light may be on or flicker on at idle.

DIAGNOSIS:
Verify engine oil pressure as described on page 9-21 of the 1999 Concorde/Intrepid/LHS/300M service manual (Publication No. 81-270-9140). If engine oil pressure is within specification perform the Repair Procedure.

PARTS REQUIRED:
Qty Part No. Description
1 05017800AA Wire Terminal/Vent


REPAIR PROCEDURE:
Raise vehicle on a suitable hoist.
Remove engine oil pressure switch connector from switch.
Remove sealing dart from the empty cavity at the rear of the connector.
Pull terminal locking ring outward from front (switch) side of connector to gain access to terminal locking tabs.
Install wire terminal/vent, p/n 05017800AA, in place of the removed sealing dart. Slide locking ring back into place.
Attach the connector back on the oil pressure switch.
Spot tape the wire/vent to follow the harness towards the top of the engine compartment.

Replace your PVC valve $10 and see what happens.

I belive they didn't reset the oil light timer. I belive the sequence is 1. key on (not acc with engine off)
2. step on the brake pedal 5 times within 10 seconds. 3. key off. 4. start car. 5. check if the light went out. you may have to try it a few times to get it.

If engine is not ticking or knocking while running, likely the pressure sender is faulty. If changing it makes no difference, have actual pressure checked with a mechanical gauge.

is it low on oil? if so it could be an internal oil leak (wouldn't be able to see) or external but you didn't say anything about that... if level is good replave the oil pressure sensor

You may need to replace the Temperature Control Sensor. Located at the engine near the thermostat housing.

It means your air filter is loose. I had the same thing happen to me a few days after I had an oil change. I took it to the dealership and they said it happens all the time, especially if you have the oil changed by someone not experienced in dealing with Scions.