Yep, Lorne has told a lot of truths, The assortment boxes are great, everyone should have one as they have a multitude of uses but unfortunately they generally don't go to large enough sizes for most sump plugs or fillers.
Crush washers are as shown by gomog here and are designed to form a seal so are the best choice if that's what is needed. Most post mid eighties cars tend to have better threaded sumps and plugs so don't tend to leak that much as they also include flanged bolt heads and machined seats. Think back( those of you who like me are old enough) and you will remember most sump plugs had small weeps even if providing a fairly good seal and often needed a sealing compound or tape as they aged. plain copper washers work fairly well but really need annealing first. If using PTFE tape or a compound like hylomar blue don't be tempted to cover to the end of the threaded portion of the plug as you do not want any of the residue to enter the engine. and when you remove the plug inspect the threaded hole in the sump to make sure all previous solutions have been cleaned away before refitting the plug. Incidentally Hylomar blue is a non setting sealing compound in that it goes off but stays soft.
Now let's look again at the aluminium sort. They really are designed to be used only once as they tear. They work in a different way in that as you tighten the plug the washer deforms into the bolt and tightly fills the void at the top as it's displaced into the shaped head of the bolt shaft and it is this action that forms the main sealing effect. So the torque setting is a prescribed force to achieve this action and no more. When removed the alloy washer should be tightly attached to the plug. Now here is the rub, If the face is smooth and intact its possible to to use it again and you'll know this if the car spec gives a range for the setting torque, say 23 to 28 ft lb, then you would use the lower set.
The manufacturer would however tell you to always change the seal! But not their shop mechanics who seem able to assess ye or nay. This only works if you do not attempt to remove the washer from the plug. While we are talking about sumps and oil, if you have the spin on cartridge type, tin can type, when you have loosened it a couple of turns get a screwdriver and puncture a hole centrally in the bottom of the can, they're not very thick. I have an old screwdriver with a shaft of about 1/4" which I have sharpened to a point. This works well but for years I used an old Phillips
, the round shaft of the screwdriver doesn't leak oil out until you pull it clear! Let it drain now and when it stops you can undo the filter fully without getting an arm full!
Points of note;
Be assured you have the correct replacement filter as there's no going back!
And again on fitting the new one, lubricate the rubber seal with oil and hand tighten only. How tight is tight enough? Well you will feel it start to tighten by degree until it stops, then grip it as tight as you can and try and tighten it further. You'll find it will tighten a little more but not much..... now walk away, no need to touch it again just a visual check for leaks on first start and short running time.
