Oil change volume difference - horizontal vs inclined drain

[FerrariF1]

I have a 2021 Mazda CX-5 Turbo. I use Motul 8100 ECO-LITE 5W-30 oil, and OEM oil filter (1WPY-14-302). I change the oil every 7500Km / 4660 miles.

The first 4 oil changes were performed at a local shop where I got to watch the process. Car was placed on a flat surface and oil drained until it dripped slowly, and the oil filter was changed while the oil was dripping. New oil was then poured in, the full 5L jug, and the oil level was 1mm above the full line. All 4 times the same process, and the same oil level. I check oil level once a month, always when cold, on a flat surface, and the oil level has always been the same.

The last 2 oil changes I performed at home, by driving the front wheels up 6" ramps, while the rears were on the ground. Oil was drained until it dripped slowly, and the oil filter was changed while the oil was dripping. New oil was then poured in, the full 5L jug, engine started, idled for 30sec, and taken off the ramps onto a level surface. The oil level checked a few hours later, and it was half way between the lower and upper dots. Poured an extra 1/2L to bring the level up to 1mm above the full line.

This means that draining the oil while the car is inclined drains more oil than when it is on a flat surface. 5.5L drained when inclined, 5.0L drained when level. Has anyone else else experienced this?

 

[yrwei52]

I have to agree with you that your observation is logical. The oil drain hole is at the back side of oil pan with a 30° angle down. If we raise the front end with a standard ramp, more oil should get drained. Many 2.5T owners here claim 5.5 quarts should get you to the Max mark for the oil change although the manual says 5.1 quarts. In my case I need 5.2 quarts for my 2.5L NA to reach the Full mark although the manual says 4.8 quarts. I do raise the front end a bit with my home-made ramp when I drain the oil. That should be considered as almost level.

 

[Conrad 16.5]

I change the oil using homemade ramps like Yrwei does. Except I place a couple of 2x10's under the rear tires. The front is still elevated more than the rear but not much. I don't have a turbo and when refilling I just dump in 5 quarts and call it good. I'm not concerned about the small amount of old oil that may or may not drain out, no big deal.

 

[GTXT23]

I have a 2021 Mazda CX-5 Turbo. I use Motul 8100 ECO-LITE 5W-30 oil, and OEM oil filter (1WPY-14-302). I change the oil every 7500Km / 4660 miles.

The first 4 oil changes were performed at a local shop where I got to watch the process. Car was placed on a flat surface and oil drained until it dripped slowly, and the oil filter was changed while the oil was dripping. New oil was then poured in, the full 5L jug, and the oil level was 1mm above the full line. All 4 times the same process, and the same oil level. I check oil level once a month, always when cold, on a flat surface, and the oil level has always been the same.

The last 2 oil changes I performed at home, by driving the front wheels up 6" ramps, while the rears were on the ground. Oil was drained until it dripped slowly, and the oil filter was changed while the oil was dripping. New oil was then poured in, the full 5L jug, engine started, idled for 30sec, and taken off the ramps onto a level surface. The oil level checked a few hours later, and it was half way between the lower and upper dots. Poured an extra 1/2L to bring the level up to 1mm above the full line.

This means that draining the oil while the car is inclined drains more oil than when it is on a flat surface. 5.5L drained when inclined, 5.0L drained when level. Has anyone else else experienced this?

YES - I thought it was wrong and rechecked cold - hot and cold again - I use rino ramps and its 6" - i let it drain for 40 minutes - , filter off , cap loose - and it was bone dry - Think yerwei52 said that the 4.8 rec was shy for full ..up to .4 qt - i put the full 5qts and its 1-2 mm of top notch full .. so im good there but it could handle 4.8 + - .2-.4 qt for totally full- or easier 5qts +.2 qts- max ( i have 23 NA )- contingent upon the drain out amount...of course
- One other factor -is my driveway is inclined and the ramps offset thatangle- not completely - but its bias towards the front being slightly higher than the rear with ramps - thus ...the plug is tilted back - which can only help - without doing a sight on the slope - no way to know -

 

[madar]

You're way over thinking this, doesn't matter how long you wait, you're never going to get all the oil out because it's not all in the pan. If you took the engine apart you'd probably find another 1/2 quart draining out. 20 minutes tops for me. Almost 5 quarts, I never fill to the full line.