So i change the oil in my toyota matrix because the dealer does it for 40 bucks and its pretty much the same thing with the pathfinder so should i just do it home? And iv looked over the maintenance book and look's like they do a shit load of *inspecting* with the oil change so does it really make a difference? And one more thing as far as oil goes any one know what the dealers use? My pathfinder turned the 40k mark so id like to put something good in it.

I use Mobile 1 synthetic with a Nissan filter. don't forget to get the crush washer also.

me&pathy wrote:So i change the oil in my toyota matrix because the dealer does it for 40 bucks and its pretty much the same thing with the pathfinder so should i just do it home? And iv looked over the maintenance book and look's like they do a shit load of *inspecting* with the oil change so does it really make a difference? And one more thing as far as oil goes any one know what the dealers use? My pathfinder turned the 40k mark so id like to put something good in it.

shit loaf of inspecting making a difference... probably not.

Dealers use conventional oil in my area. But I get my oil changed every 3 months for free till I rid of the Pathfinder. So I won't bother with synthetic as the oil being drained is still fairly clean.

If you want good oil, a lot of people out there use Mobil 1 synthetic 5w30 weight. But then, there's Quaker State also.

HillbillyJake wrote:I use Mobile 1 synthetic with a Nissan filter. don't forget to get the crush washer also.

This is something that I have only seen come up with my most recent Nissan's. What is the purpose of a new oil lug washer with every oil change. Is it supposed to prevent leaking? Is it easier to get the bolt out the next time? What's the deal, because I've never replaced one and have never had a problem.

Mobil 1 Syn users may want to do some research ..there has been some tests done that show M1 syn not up to standards ...

I do mine ..5w-30 non syn. Valvoline every 3000-4000 miles ... And I always take a look at everything ... under the hood and underneath ...

myriad46 wrote:

HillbillyJake wrote:I use Mobile 1 synthetic with a Nissan filter. don't forget to get the crush washer also.

This is something that I have only seen come up with my most recent Nissan's. What is the purpose of a new oil lug washer with every oil change. Is it supposed to prevent leaking? Is it easier to get the bolt out the next time? What's the deal, because I've never replaced one and have never had a problem.

The crush washer is there to take force off of the threads in the oil pan. However, onces its been crushed, it doesn't provide this protection any more.

Had a buddy that stripped the threads on his drain plug. It wasn't a really big deal to get fixed. Not cost wise, as it failed when he went to torque the oil drain plug, the fix was a tap and die kit and an oversized drain bolt.

Very annoying though.

t

K thanks guys im gunna change it this weekend its on my list of things to do.

@disallow:

Good to know. Thanks for the explanation.

disallow wrote:The crush washer is there to take force off of the threads in the oil pan. However, onces its been crushed, it doesn't provide this protection any more.

Huh?

The washer removes no "force" from the the threads in the oil pan. It sounds like you are confusing an engineered weak point in a structure, such as a crumple zone, with a crush washer. Or are you saying you think that because the washer begins to fail at a lower torque than required for the fastener that it's good enough because there is probably a seal and one would stop tightening at less than the recommended torque value there-by "taking force off of the threads"?

The washer will begin to fail at a lower torque than specified for a fastener, but in the end you still end up with the recommended torque value being applied to the threads on the bolt and oil pan. IE: if there is a spec of 15ft/lbs on a bolt, as you are tightening it the washer will begin to fail at 7ft/lbs and be compressed at 10ft/lbs allowing you to apply the required 15ft/lbs to the fastener. (the #'s provided are purely for example as I do not have any technical data on the washers to state when they are engineered to fail but in practice that is how it works)

The primary purpose of a crush washer is to conform to an irregular mating surface for proper sealing. There are other oil pan washers out there that have a copper metal ring fused with a rubber sealing surface that are very reusable.

blink32 wrote:

disallow wrote:The crush washer is there to take force off of the threads in the oil pan. However, onces its been crushed, it doesn't provide this protection any more.

Huh?

The washer removes no "force" from the the threads in the oil pan. It sounds like you are confusing an engineered weak point in a structure, such as a crumple zone, with a crush washer. Or are you saying you think that because the washer begins to fail at a lower torque than required for the fastener that it's good enough because there is probably a seal and one would stop tightening at less than the recommended torque value there-by "taking force off of the threads"?

The washer will begin to fail at a lower torque than specified for a fastener, but in the end you still end up with the recommended torque value being applied to the threads on the bolt and oil pan. IE: if there is a spec of 15ft/lbs on a bolt, as you are tightening it the washer will begin to fail at 7ft/lbs and be compressed at 10ft/lbs allowing you to apply the required 15ft/lbs to the fastener. (the #'s provided are purely for example as I do not have any technical data on the washers to state when they are engineered to fail but in practice that is how it works)

The primary purpose of a crush washer is to conform to an irregular mating surface for proper sealing. There are other oil pan washers out there that have a copper metal ring fused with a rubber sealing surface that are very reusable.

Not sure what field you are from, but the crush washer definitely changes the calculation for clamping force. And based on the material used (looks like 3003 or 5005 aluminum that we get up here in Canada), after being torqued, it would be fatigued and need to be replaced.

I do agree that it would also form to the non-yielding mating surfaces, but if the washer didn't have any chance of fatigue, Nissan (Honda, Toyota, etc etc) would not recommend changing this part every time the bolt is removed. And there are numerous crush washers throughout the vehicle, including trans, diffs, TX case, brake line connections, PS Connections, fuel connections, etc etc. All of these washers need to be replaced once taken apart.

Many people reuse these washers forever and ever, but as the metal fatigues over time, the torque/force that would normally get absorbed by the crush washer gets transferred to the threads in the oil pan. As I mentioned earlier, not a good failure mode.

I guess flame on... not sure whats the deal with hostility, just trying to help.

t

disallow wrote:I guess flame on... not sure whats the deal with hostility, just trying to help.

No flame or hostility here. You're acting defensive but I don't see anything in my post to warrant it. I simply questioned your statement of "....it takes force off the threads...." and gave my differing pov.

You are going over and over about replacing the washer if you don't it will fail. I'm not arguing with you on that as once used it is fatigued and potentially will no longer seal correctly. The washer, and any other crush washer should be replaced once the fitting is separated and I never mentioned otherwise.

Just about anything can change the calculation for clamping force on a fastener if you get granular enough. Oil on the threads changes the values vs a dry fastener. I wasn't thinking this finite on the example as we are dealing with low tq value fasteners with coarse threads.

What I am questioning is your statement that the washer is there to take force from the threads. This washer is there specifically to create a seal, or else it wouldn't be there at all. If this were a standard flat washer that was transmitting a clamping force from the head of a bolt over a larger area I could see that pov. But in the case of a soft-metal gasket this does not apply.

Are you referring to force being removed as in it takes less force to create the seal with the soft metal washer vs a hardened fastener on the mating surface? I would agree to that. We could go one step further and just use a piece of rubber on the bolt directly and remove even more force from the threads to create an appropriate clamp. But you've probably got a formula in your engineering book by your side that you're ready to slap me with to which I will concede that I was not looking at it from that angle.

Again, to clarify. No flames, no insults being thrown and no hostility. I'm just questioning you.

PS: The field I'm from is the interweb's tough guy affirmation club. I cruise the information highway in my shiny 78 Camaro, mullet flapping in the wind and internet peen in my hand like a sword. Don't mess with me cuz I'll argue with you on the internet!

First oil change I did I tossed the aluminum washer and went to a fiber washer ... replace it every other oil change and all is well ... the aluminum washers get crushed and leak , and are a pain to get off when replacing ....

blink32 wrote:

disallow wrote:I guess flame on... not sure whats the deal with hostility, just trying to help.

No flame or hostility here. You're acting defensive but I don't see anything in my post to warrant it. I simply questioned your statement of "....it takes force off the threads...." and gave my differing pov.

You are going over and over about replacing the washer if you don't it will fail. I'm not arguing with you on that as once used it is fatigued and potentially will no longer seal correctly. The washer, and any other crush washer should be replaced once the fitting is separated and I never mentioned otherwise.

Just about anything can change the calculation for clamping force on a fastener if you get granular enough. Oil on the threads changes the values vs a dry fastener. I wasn't thinking this finite on the example as we are dealing with low tq value fasteners with coarse threads.

What I am questioning is your statement that the washer is there to take force from the threads. This washer is there specifically to create a seal, or else it wouldn't be there at all. If this were a standard flat washer that was transmitting a clamping force from the head of a bolt over a larger area I could see that pov. But in the case of a soft-metal gasket this does not apply.

Are you referring to force being removed as in it takes less force to create the seal with the soft metal washer vs a hardened fastener on the mating surface? I would agree to that. We could go one step further and just use a piece of rubber on the bolt directly and remove even more force from the threads to create an appropriate clamp. But you've probably got a formula in your engineering book by your side that you're ready to slap me with to which I will concede that I was not looking at it from that angle.

Again, to clarify. No flames, no insults being thrown and no hostility. I'm just questioning you.

PS: The field I'm from is the interweb's tough guy affirmation club. I cruise the information highway in my shiny 78 Camaro, mullet flapping in the wind and internet peen in my hand like a sword. Don't mess with me cuz I'll argue with you on the internet!

sorry working on 6hrs of sleep in the last 48. On a positive note, got a new kid outta the deal!

disallow wrote: sorry working on 6hrs of sleep in the last 48. On a positive note, got a new kid outta the deal!

Its all good. I have been known to be a dick but didn't try to come off like that. Congrats on the kid. Best and most trying times all at the same time!

Oh, and I'm always open to being schooled. Interweb smack downs are the best.

what size is the crush ring currently installed on pathfinders?