New wr125 x just change

I think the 3.8 takes 4.5 quarts. Try this method. Pour some fresh oil directly into the filter. This help stop the engine running dry on first re-start. Then add 4 quarts and walk away for 30 minute. This lets the oil settle through the engine into the oil pan. You get a more accurate reading on the dip stick. Check the oil level BEFORE you add more oil. If it reads more than half Start and run the engine for about 30 seconds to check all the dash lights go off, there's no warning lights and the oil filter has been filled correctly.
Again walk away for 30 minutes to let the oil settle. Recheck the oil level. On the dip stick it is usually around One litre of oil between the Low mark and the Full mark so use that as reference when you top up with the last half quart. Don't add more than 4.5 quarts as too much can cause problems.

I strongly suggest you read the vehicle handbook to fully understand the meaning of the light or indicator.

If the indicator is telling you the oil level is low, the computer might be just testing the system or the oil level sensor might be sticking or faulty.
If the indicator is telling you the oil pressure is slow to build, again it might be a circuit check or it might be an important warning.

A third possibility is a warning the oil filter is ready for a change.

well let me see you have 4.6L engine you need 7.5 quarts of oil with new oil filter.to do the oil change you need large drain pan and oil filter wrench and a metric wrench to remove oil drain plug you need a funnel also.you need first start engine let it run for 5 minutes to warm up thin out the oil so it will flow better.once engine warm up.turn off the engine.open you hood.now safely raise support vechicle on jack stands make sure vechicle parked on solid level ground.place large drain pan under oil pan remove oil drain plug you need a 15m wrench remove drain plug let all old oil drain out until you see slow drip then reinstall oil drain plug dont over tighten drain bolt.then place drain pan under the oil filter then remove oil filter using oil filter wrench or large channel lock pliers.once you remove oil filter wipe oil filter seal surface with clean paper towel.take new oil filter add oil to new filter then install new oil filter hand tight take filter wrench turn oil filter one half more turn dont over tighten will damage oil filter seal.make sure oil pan drain plug is in place. then lower vechicle. remove oil filler cap on the valve cover add new oil to the engine using a funnel to keep from spilling oil all over the valve cover and exhaust manifold.add all 7.5 quarts to oil crank case wait until oil settle down in crank case check oil dip stick oil level should be at the full mark on oil dip stick.dont over fill crank case.once you finished oil level correct crank engine check for oil leaks at oil filter and oil drain plug. if engine running okay you see no oil warning lights you ready wheel and deal.

you should change the oil every 4000 to 5000 km in that hot climat your van should take a little more then 4 liters of oil so buy 6 liters oil filter part # should be on the filter you could take it off the old one if your doing this yourself drain oil put new filter in and add 4 liters of oil wait 5 minutes check oil level on dip stick add half liter at a time and check oil level again wait few minutes in between for oil to drop down in oil pan for proper readings on dip stick.repeat ontil oil level shows in the hatch marks on dip stick DONT OVER FILL. also fill oil filter with oil before instaling the new one to insure that oil will flow trought engine at startup without having to fill oil filter first leaving engine to run without oil until this happends internaly on its own you may have a liter left after your done ,you can use this for top ups inbetween oil changes .you should also check and replace your air filter at this time .

so if the level is good on the dip stick , and you changed the filter
the next obvious is the level sensor is bad.
after that your looking for internal engine problems

It's going to be hard to get the right one, as you well know, what you could try, is do a oil change with oil filter, get an after market dip stick, after replacing oil and filter, start engine, turn it off, insert dip stick, and mark it with a file where the oil level is, that will be your new full line.

first make sure oil level is up, then check or just replace oil preasure switch, if light still comes on, have your oil preasure tested, could be low oil preasure or electrical problem start there. good luck.

This engine requires synthetic oil, 5 quarts, and oil filter. Remove dip stick, remove oil drain plug at bottom of engine oil pan, remove filter housing, remove oilf filter and o-ring. Replace o-ring and filter, rub o-ring with some new oil, replace filter housing, replace oil drain plug, pour new oil in at top of engine oil cap, replace dip stick, start engine, run for 45 seconds, turn off, check dip stick to make sure oil is at correct level. You are done, recycle old oil.

The van must be on level ground while checking. after adding the correct amount of oil making sure to prime the oil filter before installing run the van for approx 30 seconds turn off and recheck after 1 min.