So recently when i start the car the oil pressure is at about 60psi then after the car starts to warm up the oil pressure drops to around 20-25psi at idle but will go back to around 50-55psi when i have my foot on the gas. Is this normal because i don't remember it ever being this low when idling. It usually sits at around 45-50 when idling and 50-55 when im giving it gas. I first noticed this 2days ago and it was about 30degrees C outside and i thought maybe it was because of the temperature or the car was low on oil so i dumped about half a liter in it and it still did the same thing yesterday.

 

Pretty common for an engine's oil pressure to be lower once thoroughly warmed up, and 20-25 psi is not low enough to cause any harm at idle. I guess my concern would be the fact that it suddenly changed from what it was previously.
Normal wear on the bearings will cause oil pressure to drop over time, but not suddenly. I'd keep a close eye on it and if it continues to drop you may have something going wrong with either the bearings or the oil pump.

 

I've had that happen to me twice, where it was a noticeable change in a short amount time. Both times it was the oil pressure switch being/going bad. Keep an eye on it, and if it changes more, start with the cheap fix first...the switch.

 

It's possible that it may be a bad gauge or sending unit for the gauge as well.My truck has done pretty much the same thing for almost 2 years now,only difference is it reads good when started and while driving,but after it warms up and sitting at idle the needle drops completely to zero,if mine were a pressure issue i'm sure it would have done damage by now.But as mentioned i'd keep an eye on things and see if it changes,or possibly try a new sending unit like camaro 69 suggested.

 

Assuming it's an electric sending unit, and not a aftermarket mechanical gauge, it could be the sending unit.

 

Do an oil change, smell the oil for gas. See if the fresh oil brings the pressure back up. A poorly tuned carb can thin oil out pretty fast, as well as wash out the rings and bearings.

My next step would be to go to a thicker oil. This is all assuming the gauge is right.

 

The gauge is an aftermarket mechanical gauge and the oil is freshly changed about a month ago it's 20w50 so ill keep watching it to see what it does....the only thing that has changed this year from last year is that it has More oil in it....the car has a small oil leak and a racing pan so It always showed about 1/8" on the dipstick, but this year I added 8 liters instead of 7 and there's about an inch showing now

 

Since it's a mechanical it wont be a gauge issue. I would check the oil as Damon mentioned to see if it has thinned from fuel in it. Could be a rich carb, but could also be a leaking mechanical fuel pump which would thin out the oil.
Try changing oil and see if the pressure comes up. That might give you some insight to the issue.

 

That's what I said. Moot point now!

 

Well since it's mechanical it is a moot point.