Oil Catch Can and UOA

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Can you see levels change on a UOA that has installed a oil catch can on a vehicle like fuel, water?
 
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Originally Posted by Bill_W
Can you see levels change on a UOA that has installed a oil catch can on a vehicle like fuel, water?


The oil and water that ends up in a catch can would have also exited the crankcase if no CC were installed. So the UOA would not show any difference.
 
Just I have seen a coincidence in raised oil and fuel levels in Skyactiv UOA tests for those that have installed a oil catch can. I drive a 2019 Miata and that is a popular install. Was thinking that the OCC was a restriction and going to be seen or just a fluke.
 
Originally Posted by Bill_W
Just I have seen a coincidence in raised oil and fuel levels in Skyactiv UOA tests for those that have installed a oil catch can. I drive a 2019 Miata and that is a popular install. Was thinking that the OCC was a restriction and going to be seen or just a fluke.

I am bit confused why the oil levels would increase from using a catch can. In theory, the oil levels should drop slightly since oil is being removed from the engine (unless I am misunderstanding what you are saying).

Likewise for increased fuel dilution, I do not see a connection between a catch can and increased dilution. Have you seen a specific occurrence of this?
 
On the ND Miata website occasionally they post a UOA. When I see fuel on it first thing I ask is did you install a catch can. Seems I can pick them out. The ones that look fine on fuel do not have the catch can installed. Kinda interesting since the Skyactiv has a oil separator before the PVC and get the intake valve over 400 C just to counter the IVD.
 
Originally Posted by 2015_PSD
I am bit confused why the oil levels would increase from using a catch can. ...
Likewise for increased fuel dilution, I do not see a connection between a catch can and increased dilution. ...
Agree. No clear reason a catch can should matter, unless in the very long term, it prevents oily blow-by from eventually causing ring sticking.
 
Originally Posted by Bill_W
Just I have seen a coincidence in raised oil and fuel levels in Skyactiv UOA tests for those that have installed a oil catch can. I drive a 2019 Miata and that is a popular install. Was thinking that the OCC was a restriction and going to be seen or just a fluke.




If I recall correctly, the SkyActiv engines already have a system designed for this. Maybe installing a catch can defeats that?

In general these engines are noted for handling fuel dilution and intake deposits better than the other GDI motors.
 
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