For the American BITOG'ers, my apology for not converting the units to imperial.
My girlfriend drives this 2008 Mazda. I've been taking over the oil changes because the place she went is bit pricey for oil changes.
The first time I did the oil change on the car was at around 145,000 KM. Given this is just a small 4 cylinder NA engine, I would expect it takes about 4 litre to 4.4 litre and indeed Mazda calls for 4 litre without filter change and 4.3 litre with filter change. Anyway, correct me if I'm wrong.
After the oil finished draining, I was appalled by how much came out of the oil pan. It was a little less than 2 litre! And the OCI was not even close to 5,000 KM. I can't say for sure the duration but let's just say it was 4 months. In other words, in less than 5,000 KM the oil consumption/loss was more than 50% unless the mechanic filled only 2 litre but I doubt it.
First of all, I was surprised by the lack of oil pressure did not trigger the low oil light on the dash. Second of all, how could a relatively young and a naturally aspirated engine consume so much oil? After all this is just a compact 4-door engine not a performance oriented engine. And more importantly how long has this been happening?
I first blame Ford for producing [censored] engines again since my family had two Fords before and both were died prematurely. Sorry if I offend any Ford fans out there and this is not my intention. I do love the Ford GTs and I believe they are built in Canada.
Then I told my girlfriend to keep a close eye on the oil level on this OCI. And again a few months had passed, on this OCI we changed at around 5,000 KM and just like the one before, only a little over 2 litre came out.
What's the reason? Some articles online says oil consumption could be caused by worn valve seals. We don't plan on spending a lot of money to nurse this car, so if it requires rebuilding the motor that's out of the question. I read somewhere that oil loss could be caused by an aged PCV which is what I plan to look at this coming summer. The worst case we would just keep feeding cheap store brand oil just to keep the car going.
A few days ago I checked the oil level again, I took note of the level both when the engine is cold and hot and I was happy to see there was not much oil loss, but what is the reason?
First, let me say this 2.3L engine has the drop-in type filter instead of the spin-on filter. I had only done two oil changes on this car. The first time when I removed the oil filter from the housing, I replaced the rubber o-ring of the filter housing cover. But I did not replace the filter housing drain plug filter because I did not have the Allen at the time and I didn't think too much of it. This design is similar to my M3.
The second time I changed the oil I do have the Allen key in my possession so I did everything properly, I did it just like how some of the YouTube DIY videos. When I took out that rubber o-ring from the filter housing drain plug, I noticed the material is not as soft as the new one that came with the filter, there was also some discoloration. I also notice there was a lot of oil stain on the filter housing cover which I could not notice the first time because I did the first oil change in the evening.
So my conclusion is that, this o-ring had not been replaced for a very long time and caused some oil leaking from the oil filter housing. It may not drip as much when the car is parked because most of the oil goes back to the oil pan. But if the car is running and oil being pumped through the filter, we wouldn't have known while we are in the car.
Sorry for the long post. If you reading this last line, you are a true BITOG'er and thanks for reading.