I have changed my oil a few times which led me to wonder a few things. My engine, according to the owners manual, takes 8.5 quarts of oil.
When I add oil, I can only add 8 quarts of oil according to the dipstick to the full line. I have seen many oil changers places add oil according to the owners manual. But in this case, I cant manage to add exactly the amount of oil the user manual says which is about half a quart less than what the manual says. So my question is, What is the correct reference for the correct amount of oil to add, the dipstick or the owners manual?
Also when changing my oil, is the correct way to check oil level right after I add the oil in or after I have cycled the engine first. Because in theory, it would make sense to check the oil level first before even starting the engine. To my confusion, I have seen both ways done before.
Best way is to add to the full mark then start the engine & check for leak’s this also fill’s the filter then recheck then bring up to the full mark on the dipstick.
Some of the M class Mercedes engines built during the 20 years have the oil filter positioned for access from above, when the filter is loosened a quart of oil is released from the filter and drains into the oil pan. The engine oil must be drained after loosening the oil filter housing. If the oil is drained, the oil plug installed then the filter loosened there will be a quart of old oil in the oil pan.
The engine must be run for 30 seconds after refilling with oil to pump oil though the new oil filter before you can check the oil level.
My cars take a little less oil than the manual states. I think the capacities in the manual are for a totally dry engine. There’s still oil in the passages and walls that doesn’t drain out. After you change it a few times, you’ll know how much it takes to get to the full mark, just go by that.
I’d go with the dipstick, unless you aren’t factoring in the filter. On my Olds, the book said 7 1/2 quarts but it took 8 1/2 quarts on the dipstick. The dealer said to go with the dipstick and the the books can be outdated. That’s what I did for 10 years with no problem. Also on my Acura, the book says the differential holds less than 2 quarts, but it takes four quarts to actually fill it. Can’t go by the capacities listed in the book.
It’s the filter. Oil filters will absorb some oil (1/2 quart is about right - depending on the size of filter).So after you add the 8.5 quarts then start your engine and let it run for a little while - turn engine off and let the oil settle back in the pan. Then the oil should be right at the full mark. This of course is assuming you’re changing your filter when you do an oil change (which you should). Years ago manuals would give you two different capacity numbers - one for oil change with filter and one without. I haven’t seen that in years though.
The last oil change I did on my car (this past Sunday), I added the prescribed 3.8 quarts. When I checked the oil using the dipstick after the oil change, it was a little higher than the full mark. That’s fine with me, and I don’t worry about it. When I used to get my oil changed at the dealership, they used four quarts and nothing bad ever happened.
As an owner of a model that has a known oil consumption issue, I now check my oil frequently. One of the questions you ask in your OP I can answer for you. The best way to check the oil level is to have run the car to full engine temp and then parked on a flat surface.I can tell you from experience, if you move the car, say from outside your garage to inside, and don’t get it hot, the dipstick level will not be accurate (mine reads low in that situation). Also, a slight incline or decline makes more difference in the level than I would have ever guessed. A half-quart of oil in that vehicle holding 8.5 or so is not going to matter much, so I would use the lesser of the two suggested amounts, then check it to see if more is needed after a full run.
I’ve always added a little less than the owner’s manual says, check the dipstick to make sure it is between the lo and high mark, then start the engine, check for leaks while it idles 5 minutes, turn it off, let it sit for 5 minutes, then top it off as required to hit the “full” mark on the dipstick.