I know some of you are gonna want to say "THE MANUFACTURER RECOMMENDS GEAR OIL FOR A REASON, DO WHAT THEY SAY". So if you don't have anything intelligent or technical to add to this, save yourself the trouble.

What do you guys think of running 30-weight motor oil in the gearbox? Would it need to be non-detergent to prevent it from eating synchros, like GL-5 non-synthetics can?

Some people have done this and claimed good results. According to this, 30-weight is dead center in the range of viscosities for 75w-90 gear oil.

Any ideas?

 

Bump.... Anyone?

 

I think maybe you read the viscosity chart wrong.

The chart says that at 100 deg C, 90 weight oil has a viscosity that ranges from 14 to 24 centistokes, 75W has a viscosity of 4 to 7 centistokes, and 30 weight oil has a viscosity of 10 to 13 centistokes. So, yes, the viscosity of 30 weight oil at 100 deg C falls between the viscosity ranges of 75W and 90 weight oils, but 90 weight oil still has a higher viscosity than 30 weight at 100 deg C, so 75W-90 gear oil will have higher resistance to film breakdown at elevated temps.

So the question boils down to, do you need the added protection of 90 weight oil in your transmission? For a track vehicle maybe not, and you can reduce drivetrain losses by running 30 weight gear oil without affecting wear rates in your transmission. For a daily driver, maybe you do, depending on how hot it gets in your part of the country.

 

You can do what BMW does and use D4 in your manual trans. But don't expect it to last very long because of the lack of shock loading.

 

Thanks for clearing that up, Stephen Max.

Good point about the film breakdown. But is that the only problem? If it is, I would think that all you'd have to do about that is add some Lucas Oil Stabilizer and call it a day...

Also, wouldn't it help to have the lighter oil when it's super-cold out? It certainly gets hot sometimes here in the northeast, but it can also get very cold...

 

BTW.... just drained and refilled with 2 qts. Lucas Heavy Duty Oil Stabilizer and ~2.5 qts. Exxon Superflo 10w-40 dino oil. Very nice after a few miles.... Really good shifting, and it even toned down some of the noise from my disintegrating input shaft bearings....

This might be a really good alternative for people who have a hard time finding non-GL-5 gear oil and need something in a pinch.

Unless, of course, someone knowledgeable says otherwise.

 

GL-4 gear oil is not like going out and trying to find diamonds, emeralds or rubies.

I don't understand why you couldn't locate GL4 gear oil in either 75w90 or 80w90. It appears that you didn't try very hard.

 

I dunno, man. When every single auto parts store I call tells me they don't have what I'm looking for (most of whom will actually tell me all about their wonderful ATFs instead), I generally take it as a sign that it's not easy to find that thing.

Call me crazy though.

 

I'm not calling you crazy. I responded to your other post, too.

I had absolutely no problem finding it at my local Mr. Lube - Quaker State GL4 75w90 installed at less than the cost of a regular dino oil change.

In British Columbia, we have nowhere near the parts availability in stores that you have in the US. That also goes for lubricants.

You might have had to go to a decent sized city to find some.

Metropolitan Vancouver (where I live) has a population of 2.1 million and I am sure I could find GL4 in various places.

I would be inclined to get that crap out of your transaxle and replace it with GL4 gear oil ASAP.

Just my Cdn$0.02!

 

Does every single major auto parts chain in the entire greater Philadelphia area count?

Of course you would. I was actually waiting for you to come in to this thread and say that.

But can you provide me with a REASON why motor oil with a healthy dose of Lucas Oil Stabilizer is worse than real GL-4? That's really what I'm after here. I know what common wisdom is, and I don't care. I'm looking for facts and details.

 

Listen bud, I don't profess to be an expert. But if I were you, I would get off my sorry a$$ and join www.bobistheoilguy.com and make my first post in the Rear End, Transmissions forum and ask some really knowledgeable people what they think. Based on what I've seen in the Fluid and Lubricants forum on the .org, you would be best to go elsewhere for an answer to your concern.

I don't believe you can't find GL4 gear oil in the metropolitan Philadelphia area. You must be looking with your eyes closed or don't know how to use a telephone.



But can you provide me with a REASON why motor oil with a healthy dose of Lucas Oil Stabilizer is worse than real GL-4? That's really what I'm after here. I know what common wisdom is, and I don't care. I'm looking for facts and details.[/QUOTE]

 

Have you tried? I can't find anything GL-4 locally. Everything is Gl-5 and everyone seems to think its ok to use GL-5 if the tranny specifies Gl-4. I just order it online

 

As I said in post 9 above, I went to my local Mr. Lube and used Quaker State GL4, 75w90 dino gear oil. I had it changed at less than the cost of a dino oil change.


Did it ever dawn on any members who can't find GL4, that perhaps they could buy it from their local Nissan stealership or perhaps some oil company bulk plant? Certainly, the stealership carries it!!!

 

Then "everyone" is most certainly wrong. It's not compatible. But it's your synchros, not mine.

 

Now I am totally confused. For interests sake, I called Metro Nissan in Philadelphia and they only carry GL5 80w90, not GL4 and say it replaces GL4. They didn't know what I was talking about when I said GL5 could adversely affect the synchros and tranny bushings.

I also called 4 local Nissan dealerships. Three of them do not use GL4 and one said they use a Texaco product that meets GL4 and GL5 specs in 80w90. None of the three who do not carry GL4 knew what I was talking about with respect to GL5 ruining synchros and bushings.

NAPA and Lordco (a province-wide auto parts franchise) do not carry GL4. Canadian Tire carries a product that supposedly meets GL4 and GL5 specs.

I then called back to the Mr. Lube where I got my gear oil replaced in February (GL4 75w90 Quaker State). They claim they are now using Esso GL4 80w90 in its place. Esso is owned by Imperial Oil, which is controlled by Exxon.

I am now wondering if the notion of GL5 ruining Maxima manual transmissions is an urban myth spawned and perpetuated on Maxima.org.

I really don't care one way or the other as I know where to get GL4 locally, but I now understand how it might be problematic to find it in some parts of the US.

 

That's his point... everyone thinks GL-5 is better than GL-4, which is what makes it hard to find GL-4.

 

1) Trusting Nissan for any technical information =
2) Time wasted calling the dealer vs google =

 

Perhaps you could steer me to the proof that today's GL5 gear oil ruins synchros and brass bushings in 4th Gen Maxima manual transmissions.

 

Here
GL5 VS GL4

 

There we go. See my predicament, Bobo?

What I've heard about GL-5 is that it contains extreme pressure additives which, in most cases, are sulfur compounds. It's those additives that people say can be corrosive to synchros made of "yellow metals" (e.g. ours, which are bronze). Pennzoil makes "synchromesh gear oil" that is yellow metal friendly, which, to me, lends credibility to what people say about GL-5.

I'm really beginning to think, though, that most gear oil isn't particularly different from motor oil aside from its viscosity properties. If you use a relatively light motor oil and combine it with a healthy dose of Lucas Oil Stabilizer to keep it together at high temps, you should be fine.

And that, of course, almost seems too good to be true. So that's why I'm asking about it.

 

Also the dealer around me still sold GL-4. And I can't recommend using motor oil in your tranny if it's not specified. I also cannot comment on some odd mixture of untested fluids in your tranny. I'm not sure how anyone could really comment as no one probably does this and no one that I know of would actually spend $ and time proving this combo is even nearly okay for your tranny. I'd probably use GL-5 as a temp solution vs what you did

 

And now what I would like to know is if the Canadian Tire Motomaster gear oil that meets GL4 and GL5 specs and the Texaco gear oil that a local Nissan dealership said meets GL4 and GL5 specs would potentially cause any harm. I know there are motor oils that meet a multitude of specs - SJ, SL, SM etc. etc.

I suspect that GL4 gear oil will be increasingly difficult to find. I did not replace my original gear oil until 56,700 miles and it had been in place for almost 10.5 years. I know Nissan has no recommended interval and my gear oil was dark and I did not like the looks of the viscosity.

I now plan on changing my gear oil every 30K and wonder if I should be stocking up on GL4 gear oil, despite the fact I have only had the current Quaker State 75w90 in place for 8 months and some 4,300 mostly highway miles.

 

It's not like there ISN'T a sticky that mentions GL5 vs GL4, LUCAS AND the change interval all in ONE thread. As a bonus it also mentions that you can send your gear oil out for examination.

Then again, people think I'm an **** for being scarcastic. At least I'm not blind

 

Contact talkinghorse and get a price for Amsoil MTG or Google Redline MT-90.

 

When you gonna learn that nobody reads the damn stickies.....

 

jeez, why not just order redline MT-90 from the internet? I bought it at a local parts store for 12 bucks a quart, which is ridiculous, but I wanted my manual tranny in very badly.

 

You just answered your own question, buddy. $12 a quart.

2 quarts of HD Lucas Oil Stabilizer and 3 quarts of Exxon Superflo 10w40 will fill your tranny for about $25, and they make it work better and shift smoother than any of the "GL-3/GL-4/GL-5" oils I've tried, which makes it the best store-bought manual transmission lubrication in the Philly area that I'm aware of.

Besides the fact that Redline and Amsoil gear oils are not available on a moment's notice, the best price I've seen for either one is $45 for 5 quarts of the Amsoil stuff. That's a lot more money. I had a leaky oil seal on a tranny that probably needed replacing in the first place, so I needed something fast that I could top off regularly. Spending $45 and waiting a few days for the oil didn't make sense.

Besides, no one would give me a good reason why not to use that stuff in my tranny. It's hard enough to be taken seriously when just asking offbeat questions like that... I figured I might as well just give it a shot, since no one would tell me either way. You have to admit, given how these forums are, doing and then posting is really the only way to get enough attention to improve the chances of getting some kind of answer from someone knowledgeable.

 

I wouldn't use motor for the simple fact that they have a lower coefficient of friction than gears oils. This is good for a motor where you want to reduce friction, but the synchronizers actually need some friction to engine the gear smoothly and quickly.

 

You know, I was thinking the same thing. But again... the Lucas/10w40 combo made everything nice and smooth. It sometimes felt like it was sucking the shifter into the gates.

If you keep the oil on the light side, that will offset the negative impact on the synchros because the oil will be pushed out of the way quickly when the synchros begin to engage. So as far as I know, you're only left with two problems: light oils don't climb gears very well, and they thin out too much at high temps. Multigrade oil with a good high-end viscosity rating (i.e. the "40" in "10w-40") helps the second problem, and the Lucas additive fixes both.

 

Please report back on how your manual transmission is shifting on the coldest day this winter, the hottest day next summer and 30,000 miles after you started this experiment if the tranny lasts that long!

 

If I put a GL-5 based gearoil in my tranny, and IF it does corrode the brass, how long are we talking here? 4-5 years? 10 years? 2 weeks?

I have heard everyone saying not to use it, but like Bobo, it's hard to find up here in Canada. Is there any documented proof from a reputable scientific source that someone can point out that putting GL-5 in a GL-4 designed gearbox will destroy it? Perhaps it came from a poor quality GL-5 brand?

Searching the forums have just posting with guys saying "DON'T PUT GL-5 OR ANY COMBO'S IN YOUR GEARBOX DUDE!" I'm begining to think it's an urban myth.

For example, at the time, my Yamaha XJ-750 required plain-jane 10w30 oil or 20-40 oil depending on where you lived. Oils back then were conventional fossil based. Now, there's synth blends, 100% synth, detergents, and all kinds of other energy-conserving types. Now I have to shop carefully for non -energy conserving oil because it causes wet clutchs to slip. 100% synths also caused my engine to weep oil as the detergents cleaned out my old gasket seals. I've since fixed it up, and now I'm using Mobile 1 5W-50 oil and she purrs like a kitten and gets better fuel milage too.

I'm not discounting the fact that there might be an issue with our gearboxes and GL-5 oils, but I've seen no documents from Nissan or any certified source saying not to do so. Until then, I'm sitting on the fence.

 

You can get GL4 gear oil at any Mr. Lube, Fork. I changed mine in February. At the time they were using Quaker State 75w90, GL4 gear oil. I checked recently and they have switched to an Esso product. Perhaps you can also get it at your local Esso bulk plant. While there pick up some Esso XD3 Extra, 0w30, PAO full synthetic oil for the winter.

 

I was hoping to see that as well. Unfortunately, no such luck. The thing had bad bearings to begin with and was destined for replacement anyway. It's probably coming out next week, which of course is long before I'll be able to tell anything for certain about how well it'll do in winter or how long it'll last. All I have to go on is the feel, which was fantastic, and MUCH better than the crap they sell in auto parts stores here.

 

okay, so call a local meat packing plant and pay them $20 to store your car in their freezer overnight.

 

I think shifting will be real hard when it gets cold out. Get some Redline MT-90 from summitracing.com I think it's $8 a qt. but works great for me in MN

 

Did you read the thread? I've addressed every point you've brought up.

 

You've already got one trashed tranny. Why don't you try your silly experiment with the rebuilt/new tranny and report back in a year?

 

Bobo - cheapest Mr.Lube shop was for conventional esso GL4/5 80w90 GL4/5 (non-synthetic) I could find was $39.95 + enviro fee and GST. If I went to full synthetic it was $79.95 + enviro fee and GST.

 

Because I don't have the cash to fix it if it fails, and I don't have the time to fly over there and make you cram it if it works.

EDIT: I still haven't heard any good reasons not to spend $25 instead of $40+ on transmission lubrication. For the record, I'm having a rebuilt tranny put in this week, and I'm using Amsoil fully synthetic because I had time to order it and I don't expect to be leaking fluid. But in a case where money or availability is a significant issue, e.g. for someone with a leaky axle seal who can't afford to get it fixed and needs to top off the fluid periodically, it seems that motor oil and Lucas can work.

Anyone who cares to disagree on intelligent, informed grounds, PLEASE say something!

 

I'll speak up! Have you discussed your experiment with any transmission shop or shops? If so, what did they say?

You should post on BITOG in the appropriate forum and be prepared to be ripped apart by more knowledgeable people concerning lubricants and gear oil than you will encounter on the .org.

Stand up and be a man, I dare you!