Do you check the oil level when the engine is cold or hot

cold --cool and on level ground ---will get false reading if check oil right after turning off vehicle oil in upper part of engine hasnt made way down to oil pan or if on tilt oil wont give right reading

coolant contracts when cold expands when hot this is normal

Do it when its cold you are Right .

For engine oil it will not matter. It will change very little whether it's hot or cold. Transmission fluid should be checked warm/hot and many times at a specific temperature. Coolant level should be checked cold. This will revert you from getting burned should you remove the radiator cap on a hot engine that is under pressure. Hope that helps, let me know if you have any questions.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Check the oil level as follows:

Park the car on a level surface with the engine idling . Slowly move the gear selector lever through all the shift positions and then to position P. Wait 3 minutes before checking the oil level.
As the illustration shows, the dipstick has a COLD and a HOT side. The oil level should between the MIN and MAX marks. Wipe the dipstick with a clean cloth.

WARNING! The oil may be very hot.



Do not use rags that could leave lint on the dipstick. The transmission is topped up via the dipstick tube. The space between the MIN and MAX marks on the dipstick corresponds to 0.5 US qt. (0.5 liter). Do not fill the transmission with too much oil, since this can result in oil being ejected from the transmission. Too little oil, on the other hand, can negatively affect transmission operation, particularly in very cold weather.

A Cold transmission: oil temperature 105° F (40° C). This is a normal temperature for the transmission after idling for about 10 minutes. At oil temperatures below 105° F (40° C), the level may be below the MIN mark.
B Warm transmission: oil temperature 169° F (80° C). This temperature after driving for about 30 minutes. At oil temperatures above 190° F (90° C), the level may be above the MAX mark.

Fluid type: ATF Dexron IIE and Mercon.

The transmission will have a hot and a cold mark, it is best to run the transmission hot and check the oil level whilst idling in park.

Oil Pressure Test Check for proper oil pressure at the sending unit passage with an externally mounted mechanical oil pressure gauge. A tachometer may also be needed, as some specifications may require running the engine at a specific RPM.

1. While the engine is cold, locate and remove the oil pressure sending unit.
2. Following the manufacturer's instructions, connect a mechanical oil pressure gauge and, if necessary, a tachometer to the engine.
3. Start the engine and allow it to idle.
4. Note and record the oil pressure reading when the engine is cold. The engine may need to run at a specified RPM, if so check the vehicle's specification.
5. Run the engine until normal operating temperature is reached.
6. Check the oil pressure reading again with the engine hot and record the value. Turn off the engine.

Compare the hot oil pressure reading to the specification. If the reading is low, check the cold pressure reading against the specification. If the cold pressure is well above the specification, and the hot reading was lower than the specification, the engine may have the wrong viscosity oil. Change the oil, making sure to use the proper grade and quantity, and then repeat the test.
Low oil pressure readings could be attributed to internal component wear, pump related problems, a low oil level, or oil viscosity that is too low. High oil pressure readings could be caused by an overfilled crankcase, too high of an oil viscosity or a faulty pressure relief valve.

level should be on max if its hot or just below the middle if cold. in order to top up oil we do it in two stages leave cold slowly fill to bottom mark, then wait 5 mins check again should be around middle if not add another 100 mils wait check again. then run car for 10 mins stop engine wipe dip stick clean then check again level should be slighty under top mark this should answer your question

All I can think is that there is fault with the type of oil or the oil pump mechanism or oil pressure switch or oil pressure relief valve. When cold the oil is viscous and the pump will have little difficulty in maintaining adequate oil pressure. As the oil gets hot its viscosity is very much reduced and flows with ease and the pump has to work so much more effectively to maintain pressure. The speed of the pump is governed by engine revs so as you 'press on the gas' that pump whirls around making pressure. As soon as the engine revs drop the hot oil slips past the pump vanes and the pressure drops. Remedy: Use a 5/40 or a 10/50 grade oil. These left number indicates viscosity when cold (5 is less viscous than 10 when cold) and the second number indicates viscosity when hot. If you live in one of the northern states and suffer very cold winters try 0/40 grade as this will cause less strain on the starter motor, battery and oil pump when starting in the cold. Try and choose a large figure (45 or 50) for the second number as this indicates a higher viscosity when hot, a good thing for older engines with greater wear and tolerances. I think it is no coincidence that the problem you have seen started immediately after you did an oil change and this should fix it. If this results in no joy check out the pressure relief valve in the engine block: a tired or broken spring will not allow enough pressure build up. The oil sender is probably OK but "if in doubt change it out". All the above are relatively inexpensive but if they fail to solve the problem its time to look at the oil pump assembly. This should be accessibly once the oil sump cover on the bottom of the engine is removed. You'll need a workshop manual, some good tools and an extensive vocabulary of expletives to call on. Enjoy!

Check oil on a level surface, and when cold, before start up. That will give the highest level posible, because you dont want to overfill. Overfilling will cause a number of problems.
Have in mind that checking oil on a hot engine, one that has been just turned off, will have a lot of oil on the top part of engine, that has had no time to drip down, and will give a low reading.