My oil light just came on i check oil is fine no knocks or smells i am about 400 miles till i am due for an oil change could it be an oil pressure switch

Sounds like a clogged oil pressure sending unit...located by the oil filter...it has a wire connector plug in...you need a special socket to remove, and replace...Your parts store can show you the part before you buy it...to help you find it.....

check your oil level, color, and smell. My guess is that the low oil pressure light is on because of literal lack of oil to pressurize. Generally when you get that light and a knock it points to major engine repair or replacing the engine. Knocks due to oil pressure can indicate many things from a bad head gasket to a stretched rod or blown piston rings. Check your coolant reservoir for signs of oil entering the cooling system as it will float on top of the coolant. By the sound of it it needs major mechanical repairs

210K Miles?
Knock for 40K Miles?
Suggest its time to replace the motor.

I would not have flushed the oil with that many miles; but you might have them change the oil and filter with a heavy weight oil if you had 5-30 try 20-30, if you had 10-30 try 20-50.
Stall after the oil change can be a co-incidence but check something was not knocked loose.

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Water doesn't have to be in oil for bad head gasket,gasket can blow between cylinders and be bad.You can drain oil to see if it's mixed with gas.You can have a compression check on all cylinders first and that will tell you what is wrong,also check the plugs and see .,timing could be off.Could have too much oil and straining the oil pump,change oil and filter and see what happens since it doesn't cost much.

Before driving it anymore I would have someone test the actual oil pressure using a mechanical test gauge to see how much , or little, oil pressure you actually have. The knocking noise could be a hydraulic lifter that is partially collapsed due to low oil pressure or a rod bearing that has been damaged from low oil pressure. If it is just a lifter that is making noise then there's a pretty good chance that the lifter will quiet back down once the oil pressure is normal again. If it turns out that your oil pressure is normal both at an idle and at highway speeds then the noise may be unrelated. You can cause some serious damage by continuing to operate any engine that is low on oil pressure even if the dipstick shows it to be full of oil. Hope this helps and good luck!

No if the oil light has flickered you have oil pressure loss some time just belive the sensor do help us out. lifter do not cause oil pressure loss pressure is built in the rotation of the crankshaft. The knock under the plenum will point you to that cylinder that is affected, (main bearing) as for a 1995 the injectors can only cause a misfire but no knocking noise,will they honor the warranty

bad fuel pressure regulator most likely

First pull dip stick and smell oil. If it smells like gas or if needed change it. If that does not solve it you have two options. Do a oil pump pressure test either pay a tech or buy the tester. Or, you can try replacing the oil pump pressure sender (sensor). If it still come on and is only on at idle, then you will be able to drive vehicle, but you have a weak oil pump, which, (in our service center), is not common on your vehicle. If you hear a low level engine knock at idle, then your bearings are worn out and I suggest you nurse this baby to get all the miles out of it before it gets worse. Believe it or not we had a customer with a 97 Olds Cutlass, 3.1l engine, lower engine knock, had internal bearing damage from coolant inside of oil. She drove the car over 20,000 miles before it bought the farm!!!

how many miles does it have , sounds like a rod bearing is bad or has turned , get the knock diagnosed to make sure

how much oil is left in the engine ?
the smoke was probaly oil burning,the knocking could be from low oil pressure,this could be very bad.check the oil and coolant levels and repost and let me know how they are.if any oil shows on the dipstick smell it and see if it smells burnt.