Level Ground - Oil Checks.

[Kidbeen]

When we read the manuals they all say that fluid levels 'should be checked with the vehicle standing on level ground', which is really common sense.

That maybe in a perfect world where we have concrete slab garages but 100% level ground is not always guaranteed. Also if you have to check it roadside you cannot always be on level ground. My garage does not have a slab and when I place a digital spirit level on the running boards it measures a forward slope of 2.6 degrees which for me is level enough to change gearbox oils etc. I wonder where the cut-off is when it comes to the degree of slope?

[BigBlackDog]

You could work it out...
basic rule is called a 1 in 60, meaning that a 1 degree offset will have a 1 unit offset over a 60 unit distance.

By example: at a guess the oil sump is about 300mm long in the meat of it (300tdi) and I think the dipstick is near the front. Let's say it is just for a giggle. So your floor is 2.6 degrees off level, so this would equate to a 2.6mm height difference over a length of 60mm. The actual length we are interested in is only 150mm, at worst, because the fluid level will still be correct in the middle. So that's 60 x 2.5 equals 150, therefore 2.6mm x 2.5 equals... 6.5mm up or down your dipstick depending on which way the nose is pointed. The dipstick is a lot closer to the middle so the error is even smaller.

A gearbox, well, my gearbox, is filled from the side near the middle, so as long as it's not on a side slope... diffs are filled from front/back, but a diff is only very short too. Similar to above, you are looking at a few mm difference. It's not going to matter that much. I give you the numbers and how I arrive there just by way of explanation. I happen to like working stuff like that out, oddly enough.

Short version is, put oil in, drive it, oil leaks out, don't stress about a few degrees on your driveway.

Rod

[Eevo]

told you the earth was flat

[Rick1970]

My shed has a slopping dirt floor, if I fill engine oil to full mark there, then take it to flat ground and check again, good 1/4” overfull [emoji21]

[Old Farang]

You could work it out...
basic rule is called a 1 in 60, meaning that a 1 degree offset will have a 1 unit offset over a 60 unit distance.
You been flying aeroplanes, mate? [bigsmile]

[JDNSW]

Side slope is usually more of an issue - many (most?) engines have the dipstick at the side. For example, the Isuzu has the dipstick on the LH side, and it is nearly vertical. The 2.25 also has the stick on the LH side, but it is on a slight slope where it is in the sump.

This can be a serious error when pulled up at the side of a road.

[BigBlackDog]

You been flying aeroplanes, mate? [bigsmile]



Just a little...

Never actually used that rule for navigation. Lots of other stuff though:)

[JDNSW]

Just a little...

Never actually used that rule for navigation. Lots of other stuff though:)

I have. Commonplace for solo pilots with no electronic navigation assistance.

[BigBlackDog]

The trick is not to get off course in the first place. [bigrolf]

[Eevo]

The trick is not to get off course in the first place. [bigrolf]

tower: what was your last known positition
lost pilot: on the runway...

[JDNSW]

Only place I have had to land and ask where I was was in PNG!

[trout1105]

When checking the fluids on your truck Regardless of how level your vehicle is you should be able to get a pretty good idea of how much oil you have in the engine, diffs and transfer case unless you are on a ridiculously steep bit of ground.
The only time it is important to have the vehicle 'Level" is when doing fluid changes.
Lets face it the Vast majority of drivers Never or hardly ever check the fluids on a regular basis anyway

[DiscoMick]

told you the earth was flat
Apparently it's not flat. Mind you, my eyes are so bad I couldn't tell anyway...

The Earth has a radius of approximately 3965 miles. Using the Pythagorean theorem, that calculates to an average curvature of 7.98 inches per mile or approximately 8 inches per mile (squared). The distance to the horizon in miles from height of an observer is approximately equal to 1.23 times the square root of the height in feet. For example 1.23 times the square root of 8 divided by 12 equals 1 mile. Inversely given the horizon distance in miles, the height in feet required to be visible equals the distance in miles squared divided by 1.513. The second example above concerning the Moon rising over a distant range also requires some topographic map calculations using the tan trigonometric function. Thus if a peak rises up 1844 feet at a distance of 10.0 miles or 52,800 feet, it will form an angle of 2 degrees with a theoretical flat horizon. The tan is 1844/52800=0.0349 or 2 degrees. However due to the Earth's curvature, it would appear as though it was only 1778 feet tall with the lowest 66 feet below the horizon.
https://www.aulro.com/afvb/images/imported/2018/03/203.jpgDisregarding refraction, on a perfectly flat plain like the Bonneville Salt Flats in Utah, if one's eyes are 9 inches above the ground, one would be able to see at night a flashlight one mile distant laying on the surface but not if one lowers their eyes to 7 inches. For example per the above diagram, that might be between the tangent point and Object B.

David Senesac Visual Line of Sight Calculations dependent on Earth's Curvature (http://www.davidsenesac.com/Information/line_of_sight.html)