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2020 AWD Select Machine Gray Metallic Mobil 1 0w20
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Discussion Starter · #1 ·
Per the manual, you want to get the car up to operating temperature, then turn the engine off and wait at least 5 minutes to check the oil level.

When I check mine in the morning, after the car has sat overnight, it's slightly below the top hole. When I check it the way the manual states, it hits the hole exactly.

I'm curious if others have noticed this as well?
 

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2020 Preferred Snowflake AWD
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242 Posts
I've read about this method as well. I'm not sure how the reaching operating temp then waiting at least 5 minutes method vs checking cold is any different. If anything, the cold level is usually slightly higher.

In any event, I changed the oil today. 4.8 qts fills it halfway up the dipstick. So I went ahead and added the addl 6 oz for a total of 5 qts, which didn't move the needle very much. Went with Mazda oil. Very straightforward oil change. Will swap it out again at 10k.
 

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2020 AWD Select Machine Gray Metallic Mobil 1 0w20
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Discussion Starter · #3 ·
It is weird. Hot level in this car is definitely higher. I think it's due to thermal expansion of the oil when hot.

I've read that in the 2.5L, it takes 5-5.2 qts to hit the top fill hole on the dipstick. Mazda may have recommended 4.8 due to the oil level rising a bit when hot, which is maybe why they recommend that method in the manual. I've always checked the oil level cold.
 

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2020 AWD Select Machine Gray Metallic Mobil 1 0w20
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176 Posts
Discussion Starter · #4 ·
I've read about this method as well. I'm not sure how the reaching operating temp then waiting at least 5 minutes method vs checking cold is any different. If anything, the cold level is usually slightly higher.

In any event, I changed the oil today. 4.8 qts fills it halfway up the dipstick. So I went ahead and added the addl 6 oz for a total of 5 qts, which didn't move the needle very much. Went with Mazda oil. Very straightforward oil change. Will swap it out again at 10k.
Did the 5qts bring it to the top hole? I noticed the same. I put in 4.8 and its at the half way mark.
 

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2021 CX-30 2.5S Crystal Blue Mica
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102 Posts
It is weird. Hot level in this car is definitely higher. I think it's due to thermal expansion of the oil when hot.

I've read that in the 2.5L, it takes 5-5.2 qts to hit the top fill hole on the dipstick. Mazda may have recommended 4.8 due to the oil level rising a bit when hot, which is maybe why they recommend that method in the manual. I've always checked the oil level cold.
I have issues reading the dipstick when oil is hot even after wiping the dipstick before check, Seems like the oil rises in the dipstick guide (overfilled by factory ?)
Maybe oil check cold the way to go
 

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GT Sport, Deep Crystal Blue
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112 Posts
Per the manual, you want to get the car up to operating temperature, then turn the engine off and wait at least 5 minutes to check the oil level.

When I check mine in the morning, after the car has sat overnight, it's slightly below the top hole. When I check it the way the manual states, it hits the hole exactly.

I'm curious if others have noticed this as well?
Not quite the same but similar.

In a former life I was a helicopter engineer in the military. When topping up the oil levels of the gas turbine engines when they were cold we always used to fill the tank to 0.5 of a litre below the full mark on the dipstick. If you filled it to full, when the engine came up to operating temperature it would dump some of the oil out of the engine. This was caused by the thermal expansion of the oil, effectively causing the oil tank to be overfilled by 0.5 of a litre. I imagine that a similar thing happens to the engine oil in our cars. Probably not on the same scale, but if you overfill your car engine with oil it has to go somewhere when it expands.
 

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2021 CX-30 S 2.5L white/black
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341 Posts
I don't have a good flat spot to check at home. I'm going to go somewhere and check on the level and then check again on the driveway slope and see where my "at home" full level is.
 

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GT Sport, Deep Crystal Blue
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I don't have a good flat spot to check at home. I'm going to go somewhere and check on the level and then check again on the driveway slope and see where my "at home" full level is.
exactly this. On my previous car, the difference between the oil level shown on the dipstick when the car was on the flat and on my sloping drive was approximately halfway between the top and bottom marks.
 
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