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Engine burning oil

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Hi there!

I dont know if this is the right place for this but i need some insight. I have this engine come in which is burning oil. Its a quite fresh build vq35 with about 3000 km's on it. running on a twin turbo setup. So i looked at the pistons and found a layer of carbon/burned oil on top of the pistons. To get this fixed it could either be the rings or the seals. Feel free to chime in with other insights. From what i can see on the pistons: there is an even burn, no wash from the edges so this gives me the idea that the seals could be the ones failing and need to be replaced to fix the burning of oil. I have attached pictures of the piston tops. In the hope that i'm looking in the right direction and not start a job which could be not the right direction. I hope you can share your insights on this. Thanks in advance!

Kind regards,


Attached Files

Heck, that looks more awash than just burning a bit of oil - it looks like there's actually oil between the piston edges and the bore!

What sort of history does the car have since the build - is this a recent development, something that has got worse over time or been like that from the start? Can you easily pull the inlet side enough to get the boroscope to look at the inltet valves? If it is that bad it should be quite clear if there is a problem with a lot of oil/deposits evident.

It 'could' also be a problem with the engine's breathing - are all the breathers clear and unobstructed, have any changes been made? If there is a lot of blow-by the air/oil mist that is normally drawn into the engine and burned may be sufficient to carry more/larger oil droplets? Have you done a leakage test?

Hi there!

Thanks for your reply and insight. As my assumption is that the oil comes from the top my next action indeed would be following the intake path and see whats going on there. if there is any oil in the intake path this can also be that the turbo is leaking oil into the intake path. This is also easy to check. And check the intake valves. Leakdown test was also on the list. i was just shocked from seeing the top of the pistons :)

As far as being told this engine always showed this defect. at least from the point that the turbo's are added(about 3000 km ago). As from you insight i will check the 2 pcv valves for flow. Currently these are going to a catch can although not showing any content.

Thanks for you feedback! i will check back with the results. might take some time with all the current life restrictions :)

Kind regards,


Very good point there, that I missed, is the turbo-chargers - some require restrictors and all require good drainage, either, or both, would cause problems - it would be clear from the oil trail if it was a problem and, as the charge cooler is usually low mounted, if there is any sign of it from the turbo's, you might find quite a lot of oil in it too.

Since you said it seems to be from when the turbo's were fitted, that would be a good place to start.

If the breathers are plumbed into a catch can, rather than the intake, that would seem to rule that out, but worth checking that side of things as well, if only for peace of mind.

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