Help! - slow leak from oil drain plug

[amram]

Hi all, so I changed my oil yesterday (thanks Rallysport Direct for the great DIY) and it went well except for one part, when I was replacing the oil drain plug crush washer the new one that I was given with the OEM subaru oil filter (this was from an independent shop, not from dealer) seemed a bit bigger than the old one that came off the car. In hindsight I guess I should have stopped and just reused the old one again, couldn't have gotten another one, it being memorial day. But I used the new one anyway, torqued plug down to 29ft-lb with a torque wrench. And now there's a slow leak, one drop every 5-10 mins or so.

I hoped that tightening it a bit might help, (since oil was last changed at the dealer so they could have over tightened it previously anyway) so I torqued to 39ft-lb, the leak slowed a bit but it's still there. That's when i broke out the calipers and checked the size, old washer seems to be about 21mm OD, the new one seems to be about 25mm OD and seems off center on the drain plug. So am figuring I probably got the wrong crush washer from the shop (it was loose, not in a packet so couldn't confirm part#)

Am relatively new to car maintenance (this was my first oil change), so wanted to know what are my options here?

Option 1 - increase torque to see if it stops the leak, how high is safe?
Option 2 - just drain all the oil out again and put new oil in and put the right sized crush washer in? I hate the idea of wasting good oil but I guess I shouldn't reuse the oil after draining it into an oil tray, or is that ok?
Option 3 - any others?

Also when I put the new crush washer on, should I tighten to 29ft-lb or 39ft-lb now?

Thanks in advance!




Old washer vs the new one, old one is about 3mm smaller in OD and seems less wide (OD to ID) too...

[sshole]

Never reuse crush washers, always use OEM. Same thing for oil filters.

If your oil drain pan is relatively clean, I'd say go ahead and reuse the oil. If you want to be extra safe, then use new oil.

[billwot]

1) I would NOT over-torque the drain plug.

2) You can re-use the oil if you drain it into a clean container.

[amram]

Originally Posted by sshole

Never reuse crush washers, always use OEM. Same thing for oil filters.

If your oil drain pan is relatively clean, I'd say go ahead and reuse the oil. If you want to be extra safe, then use new oil.

thanks! yes at this point I would use a new crush washer, I'd only reuse if I had no option to get one (memorial day, all closed)

[amram]

Originally Posted by billwot

1) I would NOT over-torque the drain plug.

2) You can re-use the oil if you drain it into a clean container.

thanks. Yes it's a new drain pan (first oil change ) so it's relatively clean for sure.

[amram]

ok, I decided not to reuse the oil (just to be safe), got new oil last night and the correct oem crush washer (Subaru-OEM-803916010) from a dealer, drained the oil, put the new crush washer on the plug, (compared to the one I had used previously and surely that was the wrong size washer) torqued plug down to spec - 29 ft-lb, saw a small sliver of oil on the edge of a paper towel when I stuck it next to the washer after 60 mins to check for leak, so tightened it a bit more to 34 ft-lb next, waited a few min and saw a much smaller sliver of oil on the paper towel. double checked the leak, paper again got wet, so tightened more to 38 ft-lb and called it a day.

This morning checked under the car, nothing had dripped to the floor so that's good, but car wasn't on jack stands anymore so I stuck my phone under and took a pic and I believe there is a drop of oil forming near the plug. ugh

Wondering if I should just tighten it a bit more, am just paranoid about over tightening and stripping the threads.....

thanks.


old washer on right - wrong size! (hope this helps some other newbie like me avoid this mistake - check the size and fitment!)



new washer doesn't protrude out unlike the old one...

[chas3wba0]

Yea the leak was definitely due to the wrong-sized washer. I usually hand-tighten until it won't go any further without me using an "unreasonable amount of force". You carry a risk of over-torquing with that method, though, and that's much worse than under-torquing. Just tighten until no drips, and not more.

[Philly758]

I hate to tell you to change your oil again for a third time, but I would recommend a Fumoto valve. Tool less oil changes, leak free, no need to locate a gasket. I bought one for my BRZ to try it out and now have one on both of my cars. I also recommend it to everyone I know who changes their own oil.

[wheelhaus]

I've reused crush washers many times and never to ill effect. I know this is ill advised, but I have never, ever had a leak, not even a smear of oil on the outside after dozens and dozens of oil changes across at least 5 different cars. The only trick is to replace the washer in the same orientation every time and never over torque it.

Anyways, do not over torque a fastener, ever. Torque values are specified because the threads stretch a small bit when proper torque is applied, kind of like a spring. Going a few lb ft over is not a problem, but hitting 39 lb ft is 35% over it's limit. You risk damaging the threads or cracking the hole, which could prevent the bolt from torquing or seatig properly ever again. Worst case, the threads get stripped or cracked, which at minimum means new threads being tapped to a larger bolt size, or more likely, a new oil pan.

I imaging after all this, a tiny oil leak may be the result of the smaller washer being over torqued and grooving into the oil pan or bolt head, preventing a new (proper) washer from mating correctly. Just a theory, but it's just a bolt and washer; not a lot going on there.

Installing the Fumoto valve may be a option, it has a lower torque rating (made of brass, not steel), but it uses a fiber crush washer that may better conform to surface irregularities. And you have the benefit of never having to remove it.