This method involves regular dipstick checking with a metric ruler and a little math. If your car is an oil guzzler (more than 1 qt per 1000 mi) then this method is kind of pointless. This method is more of a way to track slow oil consumption.
First, measure the distance between the low and high mark on the dipstick. Millimeters is best.
On your next oil change, make sure you fill the sump exactly to the high mark on the dipstick. Be consistent in how you check your oil level. Try to keep things like oil temperature and how long you wait after shutting the engine off consistent.
Pick some period of time that you will check your oil, whether it's weekly, every 1000 miles, etc.
As oil consumption occurs, the oil level on the dipstick will go down. The key is to measure in millimeters from the high mark to the current oil level, convert that to a percentage of the total distance from high to low, then factor in the amount of miles driven on the current oil change. The answer to this math question will give you an estimate of how many miles it takes for the oil level to go from HIGH to LOW. This is NOT how many quarts per 1000 miles, because it may take more or less than 1 qt to fill your sump from the low mark to the high mark.
Here's a real-world example.
dipstick measures 20 mm from low to high mark.
after 500 miles, the oil level has gone down by 2 mm on the dipstick.
The oil level has dropped 10% (2/20=.10) below the full mark. How long will it take to get to 100% (the low mark itself)?
(1 / .10) x 500 (miles driven).
1 / .10 = 10.
10 x 500 = 5000.
At the current rate of consumption, it will take approximately 5000 miles for the oil level to drop from the high mark to the low mark.
If you happen to know exactly how much oil it takes to get from the low mark to the high mark, you can then take it to the next step and know how many miles per 1 qt is consumed.
If you do this at regular intervals throughout your OCI, you can track how consistent the value is, and maybe even prove it out when you hit the low mark and see how many actual miles it took compared to what the formula was estimating up to that point.
Have fun
First, measure the distance between the low and high mark on the dipstick. Millimeters is best.
On your next oil change, make sure you fill the sump exactly to the high mark on the dipstick. Be consistent in how you check your oil level. Try to keep things like oil temperature and how long you wait after shutting the engine off consistent.
Pick some period of time that you will check your oil, whether it's weekly, every 1000 miles, etc.
As oil consumption occurs, the oil level on the dipstick will go down. The key is to measure in millimeters from the high mark to the current oil level, convert that to a percentage of the total distance from high to low, then factor in the amount of miles driven on the current oil change. The answer to this math question will give you an estimate of how many miles it takes for the oil level to go from HIGH to LOW. This is NOT how many quarts per 1000 miles, because it may take more or less than 1 qt to fill your sump from the low mark to the high mark.
Here's a real-world example.
dipstick measures 20 mm from low to high mark.
after 500 miles, the oil level has gone down by 2 mm on the dipstick.
The oil level has dropped 10% (2/20=.10) below the full mark. How long will it take to get to 100% (the low mark itself)?
(1 / .10) x 500 (miles driven).
1 / .10 = 10.
10 x 500 = 5000.
At the current rate of consumption, it will take approximately 5000 miles for the oil level to drop from the high mark to the low mark.
If you happen to know exactly how much oil it takes to get from the low mark to the high mark, you can then take it to the next step and know how many miles per 1 qt is consumed.
If you do this at regular intervals throughout your OCI, you can track how consistent the value is, and maybe even prove it out when you hit the low mark and see how many actual miles it took compared to what the formula was estimating up to that point.
Have fun
