# Motor oil filter



## Madmolecule (Oct 8, 2018)

I had my wheels off today, because I'm painting my calipers. I noticed that there is an oil filter on the rear motor on my model 3. Does anyone know how often does need to be changed?


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## GDN (Oct 30, 2017)

It does not need to be changed. The original motors on the S and X didn't have the filter. They added for extra protection at build if I recall, but there is no scheduled maintenance or required replacement. This oil is sealed in the motor and not exposed to combusion as in an ICE.

Edit - link to Tesla's service page. There is no maintenance listed for the oil and filter - https://www.tesla.com/support/car-maintenance


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## Klaus-rf (Mar 6, 2019)

GDN said:


> This oil is sealed in the motor and not exposed to combusion as in an ICE.


I'm not aware of any gearboxes that are exposed to combustion products.

And it's not sealed - since it gets hot and cools, it has to be vented. And since it gets hot, it will oxidize [faster when hot] and, eventually, requre replacement (servicing).

Additionally since it's exposed to air, it will collect moisture (usually on the cooling phase). Again, eventually, requiring maintenance.

Most auto mfgrs state that gear oil and diff oils are "Good for the service life of the vehicle". And we all know that's not accurate.

Final answer is we don't know yet. We need to make spectro waste oil tests yearly to see the actual wear rate.


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## JasonF (Oct 26, 2018)

Electric motors don't really produce much heat or friction. Most of it would come from the output gearset. So I would guess if it needs any maintenance, that schedule would be more similar to modern differentials than gasoline engines. Which would be almost none at all.


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## Madmolecule (Oct 8, 2018)

That makes since, but I have never had a oil filter like this on a differential. If there is minimal heat and friction, why did they add a filter? Electric motors have a lot less friction but Tesla has a cooling system for both motors, so I image it produces heat.


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## garsh (Apr 4, 2016)

Madmolecule said:


> If there is minimal heat and friction, why did they add a filter?


I covered this in another thread:


garsh said:


> The S/X drive units required a single drain and fill towards the beginning of the car's lifetime. This was to remove the little metal shavings created as the drive unit gears meshed and broke in. After that, the fluid should last the rest of the vehicle's lifetime.
> 
> A filter was added to the 3 presumably to filter out these little "break-in" metal shavings. The filter is the reason why it never needs to be changed. Unless the car's been submerged for an extended period of time, it's not going to be worth the hassle.


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## bwilson4web (Mar 4, 2019)

The Prius also claims "life time" oil only this is what I got when I changed it at 50,000 miles:








The used oil is the chocolate colored container. The new stuff is clear and pink. Details at:
http://hiwaay.net/~bzwilson/prius/pri_T_cold.html

It turns out the left over manufacturing debris, case sealant beads (silicon), and gear shear can and does turn the oil into an opaque stew. Cold weather testing showed there was a measurable rolling friction effect:








The "green" is the roll down distance after the new oil. The white is the baseline, original oil.

We collected ~50 transmission oil samples and had them analyzed. The oil was burdened by fine particulate matter. So when we got a new 2010 Prius and 2017 Prius Prime, I had the transmission oil drained and replaced. Oil analysis clearly showed small metal shavings and sealant particles. Neither transmission has an oil filter.

Two factors are at play:

shear down - the helical transmission gears literally split the longer hydrocarbons resulting in a loss of viscosity over time.
air bubbles - small bubbles, microscopic sized, can get crushed by the gear teeth and 'diesel' ignition. This leads to fine carbon particles in the transmission oil.
But the Toyota transmissions do not have any filter short of a screen to capture large shavings.

My understanding is there will be an annual service of my SR+ Model 3 sometime in March. At that time I will pay for a transmission oil change, get a sample, and new filter. I'll send the sample for oil analysis along with the old filter. Meanwhile, I'll do some roll-down tests in the cold weather and if we have a late spring freeze, test the new oil.

Bob Wilson


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## Feathermerchant (Sep 17, 2018)

GO BOB!
I can hardly wait. I have about 14,000 on mine now.


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## joelliot (Jan 25, 2018)

I was some reports of _Gearbox fluid service recommended_, coming up for some people. There must be some criteria the car is using to decide when the fluid needs to be changed that isn't published and likely not based on a set interval of time or set mileage.


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## JasonF (Oct 26, 2018)

Madmolecule said:


> That makes since, but I have never had a oil filter like this on a differential. If there is minimal heat and friction, why did they add a filter? Electric motors have a lot less friction but Tesla has a cooling system for both motors, so I image it produces heat.


Missed this question earlier.

Gasoline/diesel engines constantly have contaminants introduced via the air intake and fuel, and some of that ends up in the oil. The electric Tesla motors are more or less sealed, except for a filtered expansion breather. So there is very little chance of the oil becoming contaminated as is common on gas/diesel engines.

The oil also will not break down over time, because heat is oil's enemy in that regard, and there simply isn't enough heat coming from the electric motor. It (hopefully) never reaches hundreds of degrees - the breakdown point of oil - as the inside of a gas/diesel engine does.

That filter is probably there just in case some particles were missed at manufacture that might damage the motor or output gearset, or from minor friction wear of the gearset. If there are, there won't be many of them. They can sit trapped in the filter for a several decades without causing any problems, as long as new contaminants aren't introduced in any large quantity.


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