Right now i've been following the Owners manual method of heating the oil up and then letting the car sit before dip stick test. However, I've been reading all over the net that many people say the most accurate test is to check it in the morning when the car has been sitting all night, without running it first.

I'm getting different levels. Checking from cold in the morning, i'm about 1/4 of an inch over the MAX line. Checking according to the owners manual, I'm slightly below the max line.

Which is correct?

 

It seems as if there would not be that much diff between the reading times, but if I were you I'd just take a bit out until it's an acceptable level on the stick no matter when you read it...then you'll sleep better knowing there is not a concern whatsoever.

 

I believe the best method is to check the engine oil level when the engine is cold.

 

I'm just going to follow the FSM and it says to do it when the oil is warmed up. They probably wouldn't have put that in there if it wasn't necessary.

Reason being, there's a big difference for me when it's cold or warm. When it's cold, it's 1/4" above the MAX line. When it's warm it's 1/4" below the max line. If I lowered it so it is right at the max line, my warm measurement would be too low - so I'm just going with what Nissan recommends.

Some mechanic guy told me a little overfilled visible on the stick won't really harm it - there is some tolerance.

 

I have ran my ve a nearly a quart(3/4} over for many years now, no problems.

 

I feel that it's better to have a little underfill rather than overfill, so I have the level at full with a cold engine.

Too full and it could foam/splash.

It's a pain to check it warm as the oil is sometimes still draining down the dip stick, so letting it sit over night, there is no drip and I just make sure it reads full.

 

I thought about that too - so what I did was let the car sit level for 30-40 minutes, after the car was well warmed and driven. I timed it. Then checked. The cold dipstick test isn't mentioned in the manual - it specifically says to warm up the oil in both the owners manual and service manual. So I figured, because the two tests don't match - better to go with what the manual says.

The dipstick markings corresponding to the actual working oil levels in the engine - are likely calibrated for the test they state in the service manual.

Another engine machinist guy told me that it's best to keep the level at the MAX mark - to let the oil run slightly cooler than a low level...he explained why - I can't remember. Something to do with the amount of oil available to the pump or something - slower recycling.

 

Yea you want to check the oil when its cold because its less thin. Think about it, when you drive your car circulates oil all over making it not read accurately. But when its cold you don't have oil all over your dip stick dripping down.

 

I agree completely.

The auto tech's statement about getting better engine cooling with the oil at or above the "full mark" on the dipstick is really pushing a point to the extreme. While it is technically true that this will be the case, the ability to detect the very slightly better cooling capability would be very difficult to measure -- because it would be so very small.

Rather than obsess over which is better -- hot oil or cold oil measurement -- I believe it is better to pick a oil check method you are comfortable using -- and stick with it. I like the cold method after the vehicle has been sitting overnight. With the warm method, you will get much more variation in readings depending on how long the engine has been stopped before you take your reading. If the cold method has a tendency to underfill the oil sump, that is not all bad. It is much worse to have the oil foaming due to the sump being too full of oil. And the oil splash that occurs with an overfull oil sump can also cause problems.

All of the above is just my opinion. And if you do the warm oil measurement consistently every time (harder to do and more time consuming having to wait for some of the oil to drain down out of the upper reaches of the engine) you will get good and consistent reading.

Another reason I like the cold oil measurement is that (as pointed out above) you don't have to wipe the dipstick off before you take a reading. You just pull it out and the oil level is shown on the stick. This saves having to have a wipe rag handy and also does not waste oil that is spread on this rag. Not a big volume, but running high-cost synthetic oil, every little bit (saved) helps.

 

defintely cold check after sitting over night.

 

Thanks for the tips guys. I'm going to stick with the warm measurement, since it gives me the most consistent readings. I remember when I did the cold measurement and had the level at the MAX line, I then went to do the warm measurement, and it was reading really low - almost at the LOW line.

So I do the warm measurement that the service manual & owners manual recommends, and I let the car sit for 30 min on LEVEL surface. before reading. The most recent Maxima manual says to let it sit 10 min +. (they increased the time), so I just increased the time to make even more sure.

If any of you ever get free time, or feel like cross referencing, i'm curious what results you get. Do one reading in the cold morning. Then later when coming home from work get the engine really hot, then let it sit LEVEL for 30 minutes, then do the dip stick test - im curious if you get the same variance.

There could be something wrong with my engine that's causing this, who knows.

 

That seems like a wide range (between measuring cold vs. hot).

At one time, I did happen to measure the levels after waiting 30+ mins on a warm engine and don't think it had that wide of a range. Maybe reading 3/4 warm instead of full/cold.