[t-rd]

I want to bring back the attention on this one, after my ordeal with the oil drain plug stripping out drain hole's threads. I fixed it by using the Fumoto valve+high temp thread sealant. I had found an OEM drain plug that I bought as a spare a while back and found that the newer plug has been extended a little longer than the older one by 3mm.

Old one: 90009-PY3-000 -> theads are 1.5cm in length, on the left in the picture
New one: 90009-R70-A00-> threads are 1.8cm in length, on the right in the picture

I think Honda knew that the aluminum threads inside the drain hole wear out over time, so they updated this part to alleviate that issue. The longer bolt actually sticks past the threads into the pan.

JohnNH, i think the threads are wearing out, hence the oil weeping issue. It's not an issue with the washer. You should look at replacing the OEM drain plug with a fumoto valve soon.

 

[JohnNH]

Thanks t-rd, that's a good suggestion and I'll keep it in mind if I have any problem in the future. On my last oil change, I replaced the washer and drain bolt and haven't seen any leaking at all since.

Thanks to others for the informative comments as well. Although the topic of oil drain plug washer directionality probably isn't going to be life altering for anyone, I did learn some things in the ensuing discussion. And after all, isn't that one of the main reasons for a forum such as this? In particular, thanks to WDHewson and BLKFLSH. It is interesting that washers generally can be different on each side and, in cases where it might matter, there may be a preferred installation direction.

 

[BLCKFLSH]

Even if there were no advantages, as far as sealing, having the rounded edge of the washer out has a cleaner appearance, and I actually think people request it for that simple reason.

 

[mtts60]

I'm not a fan of oil drain valves on vehicles. Too much chance of a rock leaving your oil on the road.

See this thread for a visual description of why that could happen: http://www.driveaccord.net/forums/45-fluid-dynamics/360041-fumoto-not.html