Dealer overfills oil by half liter or so...Why?

Not just the dealer...even the factory does it.

I've not seen where the factory is overfilling. Underfilling? That's another story.

Both of my Mazda were underfilled from the factory.

2016 MX-5 had both the manual trans and the differential underfilled

2016.5 CX-5 had the coolant and the diff underfilled. Dunno about the trans as I've not checked it.
 
Last edited:
Back in the day, I used to notice this too, and I had confronted the dealership to show them and ask them how this happened. I was told that the amount of oil is preset by their machine so it's exactly what is specified for the car... however, the dealership doesn't allow for enough time in letting the oil thoroughly drain through the system as time is money(more cars they run through, the more money)... which seemed to add up...maybe 1/2 quart still left in the system when they put the drain plug back on... then they let the preset pump do it's thing, and you see the results of a slightly overfilled engine.
 
Back in the day, I used to notice this too, and I had confronted the dealership to show them and ask them how this happened. I was told that the amount of oil is preset by their machine so it's exactly what is specified for the car... however, the dealership doesn't allow for enough time in letting the oil thoroughly drain through the system as time is money(more cars they run through, the more money)... which seemed to add up...maybe 1/2 quart still left in the system when they put the drain plug back on... then they let the preset pump do it's thing, and you see the results of a slightly overfilled engine.
Huh...,crap like that is why I started just doing my own oil in 2017 (or 2018, I forget).
 
Honestly, dealers are so unprofessional.
From my past very few experiences doing the oil change at the dealership, it seems overfill like you’ve experienced is a norm. Every time I did the oil change at any car dealers for free oil change, including BMW, and Toyota’s free 2-year new car maintenance, it’s overfilled. I did ask the Toyota tech why he overfilled the oil even though I told the service writer at front NOT to overfill and put the wording on writing. He said he simply just followed the amount based on Toyota’s official instruction, 4.6 quarts, but my 2018 Yaris iA manual says 4.4 quarts.
 
I've not seen where the factory is overfilling. Underfilling? That's another story.

Both of my Mazda were underfilled from the factory.

2016 MX-5 had both the manual trans and the differential underfilled

2016.5 CX-5 had the coolant and the diff underfilled. Dunno about the trans as I've not checked it.
Yes I found my 2016 CX-5 which was fresh unloaded from delivery truck to the dealership in March 2015 was also under-filled on engine oil and coolant. Haven’t checked ATF and rear differential gear oil which are also been reported under-filled from factory too many times.
 
Back in the day, I used to notice this too, and I had confronted the dealership to show them and ask them how this happened. I was told that the amount of oil is preset by their machine so it's exactly what is specified for the car... however, the dealership doesn't allow for enough time in letting the oil thoroughly drain through the system as time is money(more cars they run through, the more money)... which seemed to add up...maybe 1/2 quart still left in the system when they put the drain plug back on... then they let the preset pump do it's thing, and you see the results of a slightly overfilled engine.
This could be one of the reasons why car dealers seem to over-fill the engine oil for the oil change most of the time. Most dealers have pre-set meter for fresh oil pump to make sure the tech fills the fresh oil precisely according to specified oil amount. Over-fill should be unlikely unless there’s discrepancy on oil amounts between factory specs and the real life capacity like my Toyota Yaris iA. I had been watching the oil change process several times at several dealerships and honestly those techs I watched did a good job and would wait until the used oil dripping and put back the drain plug. I’d wait a bit longer for sure but the tech definitely want to finish the oil change as soon as he can and he can’t afford to wait too long.
 
Yes I found my 2016 CX-5 which was fresh unloaded from delivery truck to the dealership in March 2015 was also under-filled on engine oil and coolant. Haven’t checked ATF and rear differential gear oil which are also been reported under-filled from factory too many times.
Yep, can also confirm underfilled ATF and coolant from the factory. I had my oil changed at the dealership for the first few years, so not sure if also underfilled from factory, but I'd guess so. I've had my rear diff oil changed once already so also not sure there.
 
Back