[awawd335]

I just purchased a new intercooler and I am considering installing an OCC (BMS seems to be the favored one from what I can find). Anyone have any long term experience with the BMS OCC? Are there any downsides to it besides having to empty it periodically? How much oil has it collected? Has it prevented oil from coating the intercooler? Has it had any noticeable effect on intake valve carbon build up?

I've found answers to some of these questions through searching and a post on N54tech, but not all. Thanks in advance for any assistance!

[kctim]

Originally Posted by splatjeff

I just purchased a new intercooler and I am considering installing an OCC (BMS seems to be the favored one from what I can find). Anyone have any long term experience with the BMS OCC? Are there any downsides to it besides having to empty it periodically? How much oil has it collected? Has it prevented oil from coating the intercooler? Has it had any noticeable effect on intake valve carbon build up?

I've found answers to some of these questions through searching and a post on N54tech, but not all. Thanks in advance for any assistance!

I was under the impression that the OCC was only a necessity if your car had excess blow-by that was pooling in the intercooler. When I replaced my intercooler for an aftermarket unit, there was zero blow-by in the bottom of the stock intercooler, so I decided it wasn't needed. Not sure why this varies so much between 335i's, some members here have so much that they need to empty their OCC's quite often.

[mike@x-ph.com]

Originally Posted by kctim

I was under the impression that the OCC was only a necessity if your car had excess blow-by that was pooling in the intercooler. When I replaced my intercooler for an aftermarket unit, there was zero blow-by in the bottom of the stock intercooler, so I decided it wasn't needed. Not sure why this varies so much between 335i's, some members here have so much that they need to empty their OCC's quite often.

It does vary a lot even within cars with same mods and mileage

[Snaggletooth]

I installed an aftermarket PCV valve and the catch can doesn't do much. I still run it as a safety precaution but it's usefulness is negligible if you do the PCV valve mod.

It's decent if you're running the stock PCV but I think you could better spend the money elsewhere if you buy a PCV valve for 50 bucks and pocket the difference.

Also, this is my experience 24k miles later.

[nikitino25]

Originally Posted by Snaggletooth

I installed an aftermarket PCV valve and the catch can doesn't do much. I still run it as a safety precaution but it's usefulness is negligible if you do the PCV valve mod.

It's decent if you're running the stock PCV but I think you could better spend the money elsewhere if you buy a PCV valve for 50 bucks and pocket the difference.

Also, this is my experience 24k miles later.

I just finally checked my BMS OCC for the first time after running it for probably less than 5k miles and it was about half full of oil so it was definitely doing it's job. I also just now installed the RB pcv valve and will be interested to see what difference it makes in another 5k....

[jwalker87]

I've had mine installed for about 20k miles, and I've cleaned it twice in that time. There was never more than a film of oil in the can, but after cleaning the intake valves myself, it's worth it even if it only helps a little bit. I obviously think so, since I bought one for my new-to-me 2011.

I can't really comment on if it helps with reduced carbon buildup unless I tear the intake off again, but I hope I never have to do that.