1. Install a Catch-Can:
Our engines already have an oil separator part of the PCV valve, but installing a catch-can will help prolong the duration driven until you need to clean your intake valves.
2. Use 5W30 Oil:
Now I'm really trying not to start another oil war, but according to Chris_Top_Her (a moderator over at Mazdas247) in this quoted post here, he noted his catch-can caught significantly less blow-by when using 5w30 oil:
3. Driving Habits, Driving Style:
I got about 50-75ml when I changed my oil plus some that spilled out when I took the cap off the hose. That's after about 7000 miles which is the longest interval I've done this far. It's also the least amount of catch I've drained since I've had the can. I drained out 5w30. The previous times I've changed my oil was usually around 5k, with OEM 0w20 moly and it produced way more catch and also the oil was always pitch black compared to the 5w30 I used for a longer period. Seems like the 5w30 is better at reducing blowby however this time I added 0w20 (not OEM).
Mazda has done research to try and reduce the amount of carbon build-up on the intake valves and noted that when the intake valve temperatures fall below 400F, carbon build-up is more prone to occur. This means two things: 1.
Doing lots of short distance driving and not allowing your engine to fully come up to temp is not good for several reasons, but mainly it keeps the engine below this temperature threshold, allowing carbon buildup to form. 2.
While the Italian tune-up is said not to do much for DI engines because fuel does not pass through the intake valves, revving your engine to redline and using fuel system cleaner on a regular basis will increase temperatures within the combustion chamber, thus reducing the amount of carbon build-up you will experience on your intake valves. This, along with regular highway driving should ensure your motor stays nice and healthy. According to some threads I have read over at Mazdas247, carbon build-up with the SKYACTIV engine seems to vary on a case-by-case basis, likely depending on your driving style and perhaps some other factors such as ambient temperature, oil change intervals, etc. But if you notice that the engine has become rougher during idle and acceleration, or performance/efficiency is not quite as good as earlier on in the cars life, these factors are major giveaways that your intake valves need to be cleaned.