The way and type washers mentioned in post # 27 are the ones that are more likely to cause damage to oil pans when installed as described!!!!!!
Also, there is a misconception of how a "crush washer" works. As the force is applied to the washer against 2 flat surfaces the actual side of the crush washer is not critical because it will crush as they were designed to in either position on the parts.
I want to point out that some DIY thoughts while they are helpful at times are not necessarily learned by number of same services and on many different platforms regarding servicing and material of oil pans composition of oil pans and drain plugs? And seldom regarding repairing damaged oil pans!!!
We do an oil pan repair at least once a month and have learned from this how to better install drain plugs and to date have never cause damage or had a "be-back" from an oil leak.
I might also mention that the use of a tool to tighten a spin oil filter is never necessary. In almost every case that a tool needs to be used to remove an old oil filter is from over tightening.
And again, is and has been a cause for so many issues removing them and also damaging oil filter adapters.

Some easy to do services should not be done by an none experienced individual.

 

"The way and type washers mentioned in post # 27 are the ones that cause damage to oil pans!!!!!!"

I don't understand. Please elaborate.

Edit - Do you mean the way I do it or the way the dealer did it?

 

Its not complicated.... more logic then not. The washer needs to fit properly on the drain plug. There are 2 sides on a drain plug washer used by Mazda and also many aftermarket drain plug suppliers.
The smooth side is the side as well we only use in the shop goes against the oil pan. The tightening force applied on the crush washer on 2 flat surfaces will insure a proper "crush" on the 2 mating surfaces. Because the soother side is against the oil pan you will not cause any damage not even washer scuffing which is sometimes caused installing the other side of the washer you described as torque is applied during the installation and the washer may rotate slightly while the tightening is done . The seal of the washer between the drain pan and the drain plug is exactly the same on both sides when the snugging up or even if you use a torque wrench.

 

I am certain that for the Subaru crush washers, the flat side goes toward the drain plug shoulder and the curved side with the hollow underneath it goes toward the oil pan. The pic in the link shows the curved side.

"On a Subaru, the rounded (tapered) side of the crush washer should face the oil pan, and the flat side should face the bolt head. The rounded/tapered side is designed to deform against the oil pan, ensuring a proper seal and preventing leaks."

https://parts.subaruonlineparts.com/...waAtJMEALw_wcB

 

First this is a MAZDA NOT a suburu!!!
I don't care what may be posted by an auto manufacture in this case.... and I stated it is what I do and what we now do in the service shop.
I also explained WHY it odes not matter which side. Most of those installation istruction were written for ease of the reader and you would be hard pressed to find even in SUBURU a CAUTIONARY NOTE not to install the drain plug washer in any other postion! lol

Now you are going to make me post my level of knowledge about such things as fasteners and washers...
Maybe go read this thread and get a better idea why I post some of the things I do.
Car Repair Advice Forum= at your own risk - Mazda Forum - Mazda Enthusiast Forums

then this one:

What do you do or have done for a living - Mazda Forum - Mazda Enthusiast Forums


And also I did say that I do this procedure having to do with a stupid fricken drain plug washer and why ..
Ok than ... this thread of simplicity in recommendation has been great entertainment! I also like that yet another member tosses in the how many years (40 lol) info doing a service..... as if that makes it totally correct, safe, may considered expanding and learning more about the whys and why nots consider a better way .
I do stress that and sometimes overly about always following the FSM (factory service manual) until at such times I see a flaw. And then try to state my methods and explain in epical information why I don't follow one. I cant change every service manual for every engine in the world but for this forum and a MAZDA I can make a better recommendations based on hands on professionally acquired experience!

 

bobp55 Dont take my last response personal I get that you are wanting to do a service correctly and the best way possible....
I have a straight to the point personality in person is the same as on the internet.

 

Callisto - Calm down.

My original question to start the thread was whether my using a crush washer that had dimension of OD 22mm, ID 14mm, Thickness 2mm (as opposed to the OEM size OD 20mm, ID 14mm, Thickness 1.5,mm) would cause any issues. I didn't really get a straight answer from that from anyone. I expected something like A)It should be ok. OR B)It should be ok but use the OEM size in the future. OR C)It could be a problem. Keep an eye out for leaks. OR D)It will be a problem. Drain your oil into a clean container. Replace the washer with an OEM size and refill the oil. But I didn't get that.

Then the thread expanded way beyond where I really wanted it to go.

I don't question your expertise and know you have done a lot more oil changes than I have.

I only mentioned 40 years because that's the amount of time I have been doing oil changes on my cars (ONLY ON MY CARS). So maybe 150 oil changes. And I pointed out I never had a leak or damaged drain pan, not that I'm an expert on oil changes, but that I think I have somewhat of a feel for it now and am probably not doing anything seriously wrong.

In the past you have been helpful in answering my posts and I have always thanked you for your help.

 

I never get excited and it takes a lot for me to go from a smile when i read threads to pounding the key board (i don't really do that it is an expression) .
I did sit back and smile when I did the math about your oil changes in 40 years time. I won't do the math estimate on my record... wow talk about history of something so simple that you really never think twice about doing. I bet you and others can remember doing an oil filter replacement and the last joker installed it so tightly that you grabbed a Philips head and harpooned the side to remove it? LOL
As for drain pugs I have a standing policy in the shop I run to look at the drain plug, if it is marred up, damaged in any way, excessive or questionable scratches around the oil pan drain plug area, dents in the oil pan and naturally any oil leaks anywhere around the oil filter or oil pan that they come get me. The camera goes into action, and I call the owner expressing needing to come back to the shop examine the findings. And then a disclaimer is needing to be sign regarding removal of the drain plug!!!! Its so bad that as a common practice every drain plug thread is chased before installing the drain plug and it is documented on the final invoice. .