My wife's 2016 Mazda CX-5 with the Skyactive 2.5L has been burning some oil as time has gone on. It has 145k miles on it now and runs pretty good. We've had it since it was 20k old and I've done all the maintenance work.
High quality synthetics at about 5k intervals, maybe sometimes up to 7.5k if time got away from me. Up until about 110k it was 90% highway miles but my wife's job changed and has driven around town alot since. Mostly short trips, stop and go, etc. Basically severe service. I've reduced the OCI to 3k since.
Regardless, it has always gone through a bit of oil and it will now be a quart low after about 2,000 miles. The oil gets dark pretty quick. I started a thread about using
HPL's EC30 engine cleaner and it turned me on to doing a B12 piston soak. So here it goes and the comedy of errors that went along with it.....
The comedy of errors.......
I took the engine cover off as well as the ignition coils and spark plugs. The two inner cylinders were close to BDC and the two outer cylinders were close to TDC. Not at peak, but I'd say about 85% there. Good enough. It is near impossible to get to the crank bolt or even the accessory drive on this engine without removing a bunch of stuff, so I wasn't going to be rotating the engine at all. Oh well.
Error #1
I have a borescope!!!! I've used it a few times, its nothing special...just a cheapy Amazon unit. I decided to put it down one of the outer cylinders and things looked fine...but then turned a bit blurry. I took the borescope out...and about 1.5" of the outer plastic cable and the lens tip was missing!!!!!! Great! I looked down there with a flashlight and the end of the top of the plastic tube was BARELY still in the spark plug threads. I was able to wrap some duct tape around a long thin file and get it out. Thank GOD! Had that dropped into one of the inner cylinders that were further down the hole....I'd be removing the head to get it out!
Okay...on the the Berryman B12 piston soak! I drained the old oil and put the drain plug back in to see how much B12 made it to the bottom of the pan when this is all done. My plan was to add a shot glass (~1.5oz) to each cylinder every 3-4 hours over the course of the weekend, putting the spark plug back in after to prevent it from flashing off. I started at noon on Friday and after the 4th 9pm dose I noticed some B12 had come up into the threads in one of the cylinders...time to re-think things.
I used a wooden dowel as a dipstick to see how much B12 was still in the cylinders. There was alot! Each cylinder had about an inch in them! Okay...no need to add more for now. I decided to check again in the morning and there was still a fair amount left in the cylinders. Okay...I don't see the need to add anymore here, it had been soaking for over 24 hours. I waited a few more hours and decided to use my fluid transfer pump to suck the remaining fluid out. I ended up sucking about 10oz out of all the cylinders. I then decided to open the oil pan drain and see how much had made it past the pistons...probably another 10oz.
Error #2
There was inevitably some B12 left in the cylinders and this engine is high compression...so no room for extra fluid. I wanted to get all of it out as much as possible so I grabbed my 5 gallon Craftsman pancake style air compressor and was going to blow out anything remaining in the cylinders. Plug it in and turn it on.....BOOM!!!! The compressor motor committed suicide and cracked the block!!!! Okay....on to plan B.
I found the fuel pump fuse and took it out. With the spark plugs removed, the oil filter pre-filled with oil and fresh new oil in the engine I was just going to have to turn over the motor using the starter to blow any fluid out. I put an old blanket over the spark plug holes to catch any B12...that stuff will eat paint! The Mazda has a push button start, not like the old school ignition switch that would allow to click it over. My concern was....how long would it take before the starting process would time out? Well it turns out that is 8 seconds. After 8 seconds the computer decides to call it quits. Fine....good enough for me!
Error #3
Well this wasn't really an error....just a calamity haha. I put everything back together and it was time to fire it up....uh.....hello?!?!? It took a good two minutes with multiple tries to get it to start. It just didn't want to start, it would sputter for a second here and there but in general nothing....until finally...IT"S ALIVE!!!!!
Actually, it was running pretty good! It sounded really smooth and quiet so I let it idle for a couple minutes and then took it for a drive. I swear it feels and sounds peppier and at idle you can barely hear or feel the engine running. Time for an Italian tune up! I took it for a 40 mile drive on the highway in "Sport Mode" which keeps the RPM's up and gave it plenty of spirited full throttle runs.
Conclusions.....
Sorry for the long winded story but I wanted to capture this for future readers. The car runs noticeably better and now has a quart of HPL EC3 Engine Cleaner and 4 quarts of Castrol Edge 5W-30. I'll be changing (and cutting open) the filter at 1.5k miles and will probably change the oil at 3k miles. Maybe I'll do a treatment of BGR-EP to see if I can free up the oil side rings a bit more. I might do another round of HPL's Engine Cleaner before switching over to their oils for good for ultimate cleanliness.
I'll post updates as time goes on to the oil burning, color of the oil and with whatever ends up in the oil filter. Thanks BITOG!!!!
