Mazda3 oil drain plug

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Hello, A quick question: Does the Mazda oil drain plug require an 8.5mm allen (hex)?

DETAILS: I did my sister's oil today and the factory original drain plug would not accept a 9mm hex and the 8mm had unacceptable play.
I tried 3 sets of metric hex and all 3 8mm tools were similarly loose. English sizes were all wrong. All were quality brand tools.

Just so you know, everything was clean, rust free and sharp edged.

I resorted to wrapping an 8mm hex with a piece of doubled (folded) aluminum foil to take up the slack.
That wasn't the first time I used that wee trick.

An allen set I have includes 4.5mm and 5.5mm so I wondered if a major manufacturer like Mazda would throw a stumbling block at the DIYer just like Saab did with their stupid tapered hex-on-a-dome oil drain plug.

Any experience here? Thanks, Kira
 
Notice my user name? My wife had a 2012 Mazda3 with the Skyactiv engine. I maintained the car for her and it took an 8MM bit hex socket. I used a new crush gasket for every oil change. New plugs are cheap and I'd get a new one at an auto parts store like Napa that would take a regular combination wrench.
 
My 2012 skyactiv takes 8mm works absolutely fabulous using Allen brand 8mm allen drive on a 3/8 socket love the system wish more used it.
 
I like the 8mm drain plug. I do my own oil changes. The 8mm helps keep some of the HAM fisted jerks from using impact wrenches or breaker bars to install drain plugs. Ed
 
On my Mazda 6 it had an 8mm hex drain plug. I replaced with a 17mm one from mazda that I can use my beautiful gearwrench zero offset long box end wrenches on. I dont want to deal with a stripped drain plug.
 
If you don't have or can't source the right size Allen key, it would make life easier if you used a common size bolt in place of the current plug.
 
Thanks to all of you.
1) OK, so it is an "8mm".
2) My sister bought the car new so it isn't any kind of replaced part.
3) I suppose sis just got a sloppily made bolt. In my entire life this was the worst fitting allen ever.
4) DEFINITELY buying a hex head drain plug before the next oil change.
5) Plug uses a 14mm aluminum flat washer as a gasket....same as the Hondas I service.

EPILOGUE: I do like how Mazda arranged the filter and plug such that one pretty much needs to remove the filter to have a clear angle to the drain plug.

Happy President's Day. Go buy a car! Kira
 
If it's poorly fitting, why not buy another replacement bolt? Don't know if you can get a regular hex head, but if it feels like the splines are poor, why not proactively replace it? Buy two, and replace the replacement after x changes.
 
My sister's in law 2012 skyactiv had the same problem few years back, although the hex was visibly worn out. She uses quick oil change places and they turned down the oil change because they could not remove the drain plug.
I ended up using vise grip pliers to remove the old plug. The brand new plug, that I got from my local Mazda dealer, also had some play when I used the 8mm allen wrench.

You simply have to be careful with these, which is not confidence inspiring when someone relies on quick lubes, or I would get regular 17mm drain bolt.
 
I've done plenty of oil changes myself on my RX-8 and CX-5 over the years, and I've never worn out the drain plug socket in all that time.
I also have several Ducatis and a pair of Porsches that use the same type of allen key drain bolts, and they haven't worn out either.

It all comes down to who performs the services, and if they take shortcuts with wrong tools.

BC.
 
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