TD4 engine oil level check

Just a quick one, do I check the engine oil when cold or when hot.

The reason I ask but it could just be me, is that when i check the oil level when cold the level is at the minimum mark on the dipstick, but when the oil is warm, its at the full mark if not a tad over?

So do I check when Hot or cold?

I have always checked when cold on every engine I have ever worked on, checking on a very hot engine can give a false reading as there might have been insufficient time for all the oil to settle in the sump.

hi engine oil should be checked weekly when cold worth dipping it a couple of times and make shore its on level ground hope this helps

Hi jedi,
As gary says, dip the stick a couple of times in it as it also happened to me that when I took it out it was below the min.mark, but after cleaning the stick and introducing it again it gave the correct level.

Thanks guys, I did dip the stick a couple of times and wiped too... seems that sometimes its nearly above the full mark then others on the min mark, I just put it down to the oil expanding with heat???

The other day I noticed it was on minimum, so the next day i went to top it up, but when i checked the level it was ok?

Will try it again on a know level surface, both hot and cold if possible.

But Idealy it should be done when cold? yes?

Make sure your crankcase breather has been renewed every 12k as when this blocks it plays havoc with the oil level readings on the dipstick.

I have the BMW modded plastic cone filter in there. Its probably just me will checking it when hot, will check again when cold.

As a rule oil should be becked when cold, when all the oil has returned to the pan. If hot it might that 1/3rd of the oil still floating around in the engine??

Right it is then. I will only check when cold thanks guys..........It just got me thinking because I have an auto box, and that needs checking at a certain temp, and the difference in the levels in the engine oil from hot to cold vary from min to max when hot and cold.... will do some more accurate tests and report back....

Any ideas as to how to tell the hippo is level or not......I`ve had spirit levels on the sill and lower front door frames when checking the auto box, in the end I went for the level of the front sub frame cross member underneath the car......... A but too anal or what??????

I can`t tell whether its level or not, what to you guys go off? A flat bit of road?

I have a theory about the perceived low oil level. The dipstick tube dips into the surface of the oil a certain amount. When driving the oil moves from side to side in the engine and uncovers the bottom of the tube and allows air in. When the oil then tries to find its level again, it cannot return to the original level as air is now trapped in the tube (the top of the dipstick has an 'O' ring fitted which makes it a air tight fit in the tube). Thus, when the dipstick is first removed after a run the level is shown at the bottom of the dipstick, which, when reinserted, shows the correct level, as the oil level in the tube has risen to its stable position. Just a thought! Eric.

ertin said:

I have a theory about the perceived low oil level. The dipstick tube dips into the surface of the oil a certain amount. When driving the oil moves from side to side in the engine and uncovers the bottom of the tube and allows air in. When the oil then tries to find its level again, it cannot return to the original level as air is now trapped in the tube (the top of the dipstick has an 'O' ring fitted which makes it a air tight fit in the tube). Thus, when the dipstick is first removed after a run the level is shown at the bottom of the dipstick, which, when reinserted, shows the correct level, as the oil level in the tube has risen to its stable position. Just a thought! Eric.

Click to expand...

Could be true, but I would expect after a few dips and wipes all air presure would have disapeared????


How You All Test Your Oil Levels!!!!!!!!!!!!.....................Just out of interest!!!!!!!!!

Hi Jedi, you are right about the air pressure disappearing after the dipstick is removed. However, the indication of low oil when the dipstick is first removed is a known issue with TD4 engines - you should always wipe the end and reinsert it to see the correct level. As for not seeing the correct level after reinserting dipstick, I found the same problem, but I think the end of the dipstick, which is a thick piece of red plastic at the end of the dipstick picks up oil when being lifted in and out of the tube, thus making it difficult to see the correct level. The level on mine never moves from one service to the next (10 - 12,000 miles per annum, 74,000 miles MY02 TD4) so I must admit I don't check it that often! Regards Eric.

It defianatly picks up the correct levels, I wipe it clean, and when dipped it stays on the dip stick to a cetrain level, It does not pick up any oil on the way down, if thats what you mean.

Also, if you remove the oil filler cap prior to checking the oil that will eradicate any air pressure differences in the system.

I always disregard the first reading or two and have a tendency to take the third as most accurate.

I thought the theory of trapped air in the tube was impossible due to the small hole, near the top (1.4 cm down) in the side of the tube but when measuring this little hole, which I thought was meant as ventilation hole for the tube, falls right between the two O-rings on the dipstick, so there goes my theory. Also it can't be a vent.hole as otherwise the problem of the blocked crank case breather filter couldn't give the disastrous results (see the picture of the "oily freelander") it sometimes does.