My shifter runneth over -- oil in shifter assembly. Normal?

[LeonV]

I can recall having that argument some years ago. I wasn't trying to start it again; simply saying what the manual says capacity wise. Also listed under 'approximate refill capacities' is engine oil and I've never added any more than the FSM says except on my roadster which had an aftermarket deep oil pan. I actually don't see where it says to fill to the plug in either the manual trans section or the general info section. Now, I'm talking the 280Z FSM not the 240Z FSM. If it does, you don't need to show me because, at this point in time, at least for me, it's a moot point.

I've rarely 'topped off' the oil level on any vehicle I've owned except for the few I owned that either 'used' or leaked oil. So, yes, in most cases I would do an oil change and use the recommended amount of oil and not really worry much about it between oil changes. With differentials/transmissions we're talking about much longer intervals than engines obviously so, unless the trans or differential was leaking or showing so other sign of low oil/lube the only time I'd bother with them is when I did a diff. or trans. service in which case I'd drain them before I'd refill them. This is Sarah's thread and it needs to get back to her topic. All I did was state what the manual says about capacity. I didn't ask for any technical advice nor is anyone bound to approach that area of their vehicle(s) as I do. In fact, I don't think I've ever asked for technical/mechanical advice in my 10k+ posts here.

The 280Z FSM, as well as the rest of the Z FSMs state that the transmission and differential must be filled to the filler plug. Reference page MT-5 in the 280Z FSM, as it clearly states, "remove filler plug and fill transmission with recommended gear oil to the level of the plug hole." You quoted approximate numbers from the manual but did not state what it says about capacity, otherwise we wouldn't be having this discussion. The point of my reply is to clear up for others about how Nissan tells you to refill their gearboxes.

Back on topic, no, you cannot overfill the transmission if filling through the filler hole on a level surface.

Edited November 30, 2011 by LeonV

[Zedyone_kenobi]

The 72 FSM clearly states the transmission capacity is 1.5 liters. That is what I filled mine to, and no it did not pour out of the fill hole. I did however measure the amount of fluid that I took out ( a practice I highly recommend to everybody) And I removed 1.6 liters as I filled to the fill hole last time I changed fluid.

[beermanpete]

I'm going to have to study the anatomy of this thing. Do you know where the breather vent is?

As for checking the oil level... Ooph! The reason I had the Z specialist change the oil was that I couldn't get either of the plugs loose in the first place! Maybe they're less welded into place now that he's broken them loose.

Is it even possible to overfill the transmission? Don't you fill it to the brim at the level of the fill plug?

I'm betting on the breather vent. I hadn't thought of that.

The breather vent is on top of the transmission a few inches forward of the shifter. See the attached diagram. I doubt you will be able to do much with it while the trans is in the car.

If the oil was checked/filled while the car was on a service lift the car was most likely level and therefore the oil level is likely correct. My comment about this was thinking that the oil was filled with the rear end on jack stands and the front wheels on the ground which places the trans at angle, raising the check plug in relation to the front of the trans. And yes, you simply fill with oil until it starts to run out at the bottom of the check plug hole.

[Zed Head]

When was the last time you looked under the boot? It could be a pool of oil that's taken years to build up in there. As the shaft moves back and forth maybe it's been moving a tiny amount of oil one way more than the other. The seals aren't perfect. Just a possibility.

You might dry it out, drive it and see how fast it fills up. Count how many shifts you make so that you can determine an oil removal maintenance schedule!

On the other hand, it's a good reason to take something apart that hasn't been messed with for a while.

[doradox]

I've rarely 'topped off' the oil level on any vehicle I've owned except for the few I owned that either 'used' or leaked oil. So, yes, in most cases I would do an oil change and use the recommended amount of oil and not really worry much about it between oil changes. With differentials/transmissions we're talking about much longer intervals than engines obviously so, unless the trans or differential was leaking or showing so other sign of low oil/lube the only time I'd bother with them is when I did a diff. or trans. service in which case I'd drain them before I'd refill them. This is Sarah's thread and it needs to get back to her topic. All I did was state what the manual says about capacity. I didn't ask for any technical advice nor is anyone bound to approach that area of their vehicle(s) as I do. In fact, I don't think I've ever asked for technical/mechanical advice in my 10k+ posts here.

Just in case you didn't notice I didn't offer any advice, I asked some questions.

[Willoughby Z]

... Count how many shifts you make so that you can determine an oil removal maintenance schedule!...

[sblake01]

Just in case you didn't notice I didn't offer any advice, I asked some questions.

I should have seperated that into paragraphs. The statement beginning with 'This is Sarah's thread...' was a generalization; not specifcally directed at anyone. I'm done with this one.....

[sblake01]

Oh, one other thing that kind of got lost in the shuffle. About the brass bushings. I tried those a couple of times and in my experience, thery're fine until they start to wear. Brass, being a rather soft metal, they then begin to loosen and vibrate and that metal against metal vibration is worse than when the nylon/plastic ones begin to wear. At least, that was my experience....Drove me nuts and I went back to the oem type. YMMV....

Edited December 1, 2011 by sblake01

[FastWoman]

Well, so... not getting into any arguments here, I think I'm concluding that the transmission couldn't have been overfilled if it was level when the work was being done. The guy has a lift and used a breaker bar to free the plugs, so I'm guessing the fluid change was done level. I'm further guessing that there's some asymmetry in the oozing back and forth of oil. I'll look to see whether there are any vent issues. (Thanks, Beerman! )

Zed, I've never seen under the boot before, so I don't know the leakage rate. I assume it's slow, or at least that it has some sort of equilibrium, because I have no spots in the driveway. I could tell that some of the oil was old, because it was a bit black. I'll try drying out the area and looking for leaks while I shift. Maybe I'll find what's left of the prior nylon bushings. I presume after I pull out the oil that I should put a bit of grease on the moving parts?

Steve, I've heard good things about the brass bushings, but the rattling issue makes sense. (I was wondering about that.) The problem with the nylon ones is that they don't last. Maybe I'll just change out the brass ones every several years when they start to rattle!

[zKars]

Due to extreme boredom last evening sitting in an airport waiting for a late flight I took the time to look at every FSM I had handy to understand the "facts" about this fill nonsense.

-72 barely mentions more then "put the transmission back in when your done working on it"

-73 at last mentions you should fill it after re-assembly.

-by 74 it actually says "fill to the level of the fill plug".

-This continues until 78 where they revert to saying little more than "don't forget to fill it."

-The next FSM I have is 82, and it again has gone back to saying "fill to the level of the fill plug".

- Most of the above statements are accompanied by a note about the capacity to use, some say to refer to the tables.

The pages and sections where these points are made vary from FSM to FSM, though always in the "transmission" (be it TM, early, or MT, later) section. It did find it once on MT-5, but that varied as well.

So guess what, each of you are all "right" in the scope of your personal experience, what you've read in your personal FSM study, heard on line here or elsewhere.

I came from the "find the specs & capacity table and put in that much" school. How could following that logic ever be 'wrong' after all? (this is my "right" in my realm of how things work). Never noticed any mention of approximate, and I've never seen the statement in (some of) the FSM's about "fill to the plug level" until I read more carefully and widely. Every tranny I've ever filled NEVER overflowed or even dribbled when I put in the official" amount, so the concept of "fill to the plug level" was "wrong" to me.

Being level is never simple to achieve or measure, so I'de never use the "fill until you begin to make an environmental disaster" approach. Again, all from my perspective of how things work. Seems even Nissan is not a perfect guide on the subject either. Frankly it is not possible to tell which approach is correct. If your transmission stays working, you have the correct method for you!

So from now on, when someone makes a point that appears in-accurate from your perspective, please consider that there may be an opportunity for learning opening before you, rather than a chance to criticize.

JMTC

[240Z-Fan]

All,

The reason the manuals say fill the TM to the level of the fill plug is because the level matters; the actual volume does not. The reason the level matters is because the engineers determined the fill level required to keep the gears immersed in oil, even while cornering at high g's*. Too low, and some parts get starved for oil (Older Honda's are known to lose 5th gear if the oil level is allowed to get too low.)

However, having the oil level set too high will cause the oil to get whipped up by the gears too much and foam, reducing it's ability to lubricate. It will also tend to beat up the oil faster and loose some of its carefully engineered properties. Finally, it will cause unnecessary drag thereby reducing fuel economy.

Mind you, this is not a precise science, but it is more precise than simply focusing on the volume.

The reference to the fill volume is so that you have some idea of how much you need to buy before draining it. Part-to-part variation will result in some transmission cases having a slightly larger or smaller interior volume. The important thing is that the fill level is correct because that is what the manufacturing process engineers control most tightly in order to get the expected lubrication.

Al

* In a quasi-static state, cornering at 1 G, for example, will put the surface of the oil at a 45 degree angle to the normal level (assuming the car doesn't lean). At that condition, the gears must still be partially immersed in oil in order to properly splash lubricate.</SPAN>

Edited December 1, 2011 by 240Z-Fan

[LeonV]

Due to extreme boredom last evening sitting in an airport waiting for a late flight I took the time to look at every FSM I had handy to understand the "facts" about this fill nonsense.

-72 barely mentions more then "put the transmission back in when your done working on it"

-73 at last mentions you should fill it after re-assembly.

-by 74 it actually says "fill to the level of the fill plug".

-This continues until 78 where they revert to saying little more than "don't forget to fill it."

-The next FSM I have is 82, and it again has gone back to saying "fill to the level of the fill plug".

- Most of the above statements are accompanied by a note about the capacity to use, some say to refer to the tables.

The pages and sections where these points are made vary from FSM to FSM, though always in the "transmission" (be it TM, early, or MT, later) section. It did find it once on MT-5, but that varied as well.

So guess what, each of you are all "right" in the scope of your personal experience, what you've read in your personal FSM study, heard on line here or elsewhere.

I came from the "find the specs & capacity table and put in that much" school. How could following that logic ever be 'wrong' after all? (this is my "right" in my realm of how things work). Never noticed any mention of approximate, and I've never seen the statement in (some of) the FSM's about "fill to the plug level" until I read more carefully and widely. Every tranny I've ever filled NEVER overflowed or even dribbled when I put in the official" amount, so the concept of "fill to the plug level" was "wrong" to me.

Being level is never simple to achieve or measure, so I'de never use the "fill until you begin to make an environmental disaster" approach. Again, all from my perspective of how things work. Seems even Nissan is not a perfect guide on the subject either. Frankly it is not possible to tell which approach is correct. If your transmission stays working, you have the correct method for you!

So from now on, when someone makes a point that appears in-accurate from your perspective, please consider that there may be an opportunity for learning opening before you, rather than a chance to criticize.

JMTC

Not according to Nissan. Take a look at the FSMs again. I don't have time to sift through each one, so I'll use the '72, '78, and '81 as examples.

Page GI-10 of the '72 FSM clearly states, "approximate refill capacities" in big, bold letters. Not any single transmission, engine and differential are going to be exactly the same. The 240Z is lacking in information however, and not just in this section. They assume you will fill to the plug.

Page MT-5 of the '78 FSM does state to fill up to the plug hole.

The '74 and up FSMs all state to fill to the fill plug, they never tell you to fill exactly "X" number of quarts, and the 240Z shares the same differential as other S30s and S130s, therefore, you should fill then all to the fill plug (notice I don't say until overflow). This is also clearly demonstarted in two photos (trans and diff) on page MA-25 of the '81 FSM. End of story. This is simple logic, folks.

Gearboxes are designed to have a certain oil level in them, not an exact volume. Approximate fill capacities should only be used to make a decision on how much oil to buy.

You can do whatever you want to your car, but if your procedure is incorrect according to the manufacturer and the recommendation is given out publicly (like an internet forum) then it must be corrected. Don't take it personally, you can do as you wish. I'm not telling you what to do, just informing everyone of what should be done by design. Unless maybe you know something that the engineers don't and have a good reason to change the procedure...