Manual recommends SAE90 - what brand / weight does anyone recommend for here in southern california ? Most parts places have SAE 75W/90 or 85W/90 - Not sure i want to go with Swepco - but could be convinced - road use only !
Yes, I did search, didn't find a firm conclusion.

GL5 rated...pick a dino oil.

Rich

Swepco 201

ANY good dino GL-5 will be fine, 80/90 or whatever is close to that. NO GL-4, no mixtures, AND NO moly based additives. EVER. Takes about 5-5.5 pints, and it generally comes in 1 qt containers. Remove the fill plug first! Might not want to drain it all out and find you can't refill it ............. BTW, gear oil doesn't "wear out", so changing it is required only to observe what's stuck to the magnet on the drain plug, or because you have a problem and need to disassemble the tranny.

The Cap'n

WHUT HE SAID ^.....


Oh, and if you can't get the plug out, at least top it up. Usuallly some gets away. And Mobil 1 synth will NOT work. It's too slippery for the synchros to work.

I've had real good luck running AMZOIL in my 901 boxes for the past 20 years.
My boxes shift great!

Funny, I met up with the local Swepco rep last weekend for a case of 502 oil additive...and when we spoke of my 915 box. He mentioned that many are running 90/140 or 80/140 or some thing like that.....mentioned that it worked better than the 80/90. My old Porsche Master Tech and I are going in on a case of this stuff for my 915 and 901...oh forgot we are going with the 202 /212 ...the one with moly in it.

Why no moly? or is it because of the limited slip?

Well, I have to say that I use Mobil 1 75-90w with great success despite the warnings against it from everyone and their brother including Bruce Anderson. My tranny shifts like butter with never a grind. You'd never know it was a 915. Now everyone and their brother, sister, great aunt and two year old son and pet dog will tell you that Mobil 1 is too slippery but personally I have never had a problem, only much better shifting. I used the stuff in my 901 then the 915 as well as my 911 with a 915 and all shifted MUCH better. They were all fresh trannies though. These trannies have different syncro systems than modern day transmissions and that is why the warning about avoiding synthetic.

If I had an old tired tranny I would probably stick to dino oil. If the tranny was fresh, I wouldn't hesitate to use synthetic in a street car....let me repeat....a street car because when street shifting you are typically shifting pretty slow compared to racing and my experience has been all positive with no negatives.

You will find that people will swear by all kinds of oils mainly because that's what they have had good luck with and I'm no different. I like Mobil 1.....Your mileage may vary and the sky might fall if you use it.

While gear oil isn't exposed to contaminates from engines like motor oil it can suffer from heat break down. Our cars have hot air cooled engines that blow heat around our trannies and the heat exchangers don't help much. Synthetics have a much higher tolerance to heat than dino oils.

I don't want to start an oil war so I'll just say try it at your own risk and expect that everyone will discourage its use.....

What limited slip?

Moly makes everything slippery, and the Porsche style synchros work by friction. Get the picture? And once the moly is in there, it doesn't really come out. It's a "feature"! Probably works fine in VWs, Chevys, and G50 trannies.

The Cap'n

He can't be that old, because we went through gear oils in Porsche school in the '70s, including all the reasons for using GL5 instead of GL4, and why you don't want moly in your Porsche gearbox. Maybe not that much of a "master tech", either. What ever that is ...................... Might wanna find a new one. As for the Swepco rep, he's a freakin' SALESMAN, and his lips were moving!

The Cap'n, Swepco free since 1964

I put Royal Purple gear oil in my 901 and its been working very good.

I have found Motul FF LSD to be excellent if you want to use a synthetic, http://www.motul.co.jp/eg/product_line_up/...box/gear13.html , although its not cheap.

I made the mistake of putting swepco in my gearbox once. Never got it to shift again. I've just been driving around in 2nd for 8 months now.

edit: seriously though, I've got it in all my 901 boxes and it's good stuff

I agree, none of the gearboxes I've worked on, including the one I drive around, work anymore because of swepco. Sorry, that was they all work beautifully, so easy to get the two confused.

Would you have to have a working car to know how your transmission shifts with whatever oil?

Shift free for two years!

There are of course Porsche 901/911 and 915's with limited slips - I know you know this.

Interestingly, the recommended (by Steve Weiner...) gear oil for Porsche/ZF LSD's is moly-bearing Swepco 203. I have used 203 in my non-LSD Type 911 transmission and it shifted (i.e. synchronised) no worse than before (which was not great, especially 2nd...). It has a grey but not black cast to it so my impression is that there isn't -much- moly in it...

I've used some sort of moly disulphide additive in most of my Porsche boxes, and all of the newer cars, with no discernable ill effect. I'm sure a part of it comes to technique. I once drove a car a couple months with no clutch when money was really tight. If you can shift without needing the synchronisers, you probably won't notice if they're a little less than optimally efficient.

So I don't recommend moly in a Porsche trans/diff either -- but I use it. The Captain is right - the good news is, it hangs on for a long time. The bad news is, it hangs on for a long time... So don't be thinking you can just drain it out if you don't like it.

If for some reason I were determined not to use Swepco in a Porsche box, I'd probably use Royal Purple's 90-140. The viscosity is right and it is a GL-5 lubricant. I would not use the 75-140 unless I were in someplace seriously cold.

I didn't mean to imply Swepco gear oils are bad, just expensive and unnecessary. The most important thing is to use the CORRECT product for the application. And, of course, remaining free of the cult. I DO know there are a FEW 901s around with LSDs, but the original question led me to conclude the person asking may have thought they all came so equipped. The Cap'n

Thanks cap'n, and all.
Engine and box are out, all drained , ready to refill and reinstall - is next!

AMZOIL

This is how it shifts with the Motul
http://www.youtube.com/watch?v=pIaEZFt1_D4

Gotta love a good oil discussion!

Ok, as a British car owner as well, I am used to using only GL4 and the like. The reason is that GL5 lubes have a compound in them that breaks down brass components. Maybe only British Brass, but we never use GL5. Doesn't the Porsche 5 speed have brass syncros?

And Synthetic is dino oil that has been engineered or 'filtered' to have only those molecules that have longer strings that produce better 'slippery' properties. It still is crude but on steroids.

So what is it? GL5 to be sure, but brand? Good ol Castrol, or royal Purple, or ??

Not to worry. Porsche uses iron synchros.

As per the brass, there are a lot of different brasses alloyed for different needs.
For example naval brass is an alpha-beta brass containing tin, resistant to seawater.

Find out more about the compound in GL5 lubes. We are putting brass caged bearings in the tranny, so it would be nice to know. Hopefully, it's a tale like Swepco.

Ken

...when discussing Porsche transaxles (901 & 915) and the use of Royal Purple gear oil (with the engineers at Royal Purple), back in 1995, they spoke of many Porsche owners, on an off track, having gear mesh problems with Royal Purple's thicker boundary layer on the flat face gears and inhibiting engagement.
Royal Purple's engineers suggested, just for 901 & 915 transaxles, to use their version of ATF instead of their manual gear oil.
Some users were skeptical, and ran another gear oil, some are still running
Royal Purple's ATF on track.
Borg-Warner type gearing have no problems with the thicker boundary layer of manual gear oil because of their tapered design.
If you give Royal Purple's engineers a call, you will find straight talk.

My discussions with them stemmed from friction studies on rotorcraft intermediate and main gearboxes, and studies on the JSF Liftfan, using a light weight oil in a gearbox that spins up from zero to the reduced output shaft speed of the engine, when engaged.
The boundary layer's ability to carry load, with the absence of particulate contamination, and continuous thermal transfer are key.
Every lubricant has its' own quality and use. Automotive uses are well within the working envelope of limits. Of course, as with all things, some oils are better than others.
I have used a light machine oil on tests for ACMs (think exhaust turbine) that took an acceleration from zero to 15k instantaneous and a rapid ramp to 70k rpm with a lubricant delivery of two drops per minute. Its' friction level was flat line, and the distribution histogtram was a perfect statistical bell curve, which means no friction events leading to thermal stress, and progressive failure. The oil was clear and thin as sewing machine oil.

Oils do get "tired" from thermal cycling, water vapor and particulate contamination. Transaxles that have been sitting for a long time, that have vents, as do the 901 and the 915, have two problems, water vapor attacking the magnesium and the oil itself breaking down and separating.

The transfer case in my Titan specifies ATF and as soon as I got it (with 56k mi on the vehicle, no idea how much on the oil...) I dumped whatever was in there and put in Mobil-1 ATF -- I still had a bunch on the shelf and it was winter. Plus or minus a little ATF is what - 5-weight?

Now that it's spring, I've put in Royal Purple's "Manual Gear Oil" which is rated at 10-weight. Sounds like it might be just the ticket. I still use R-P 75W-140 in the front diff and 90W-140 in the rear diff. Titan diffs are known to be a bit on the weak side so I'm taking no chances... I use a tube of LubroMoly Gear Supplement in each case.

Nissan calls for a special tricko- synthetic ATF in their transmission and while several people say there is an AMSOIL ATF that is compatible and works fine, I expect I'll be conservative for at least the first fluid change and go with the factory-specified 'Matic-J' even though the vehicle is just out of warranty.

I just drained a 901 box out of a 76 /4 I had plans to refurb this next WE in Vancouver with the good doctor. I was expecting foul smelling sludge but instead out poured some very clean purple concoction ~?
I checked the magnet and its relatively clean as well.
Now Im rethinking messing with this box.
If I was going to just refill and top up how would I ID this gear oil to match it or is there an issue with mixing gear oils?

I recently had a discussion about this, and the factory recommended gear oil changes every 10,000 miles.

I beginning to think this is ATF?

If it were ATF I would expect that it would be leaking pretty bad, no?

I can tell you from recent personal experience that Royal Purple gear oil is, indeed, purple and does not smell bad. You have to guess the viscosity but there's no confusing 90 for ATF.

Total fill is only 5.3 pints - I think I'd dump whatever's in there and put in a known quantity. I have started to see RP stocked at my FLAPS or Summit's prices and service are good (I ordered a case of 5-30 and some other bits on Thursday and it was shipped FedEx Ground (Home) so it will be here today (Saturday) so I can do all that stuff over the 3-day weekend instead of having to try to rush it before the ECC.

I still prefer Swepco in my Porsche gearboxes but there are plenty of people who like something else and the reality is in street service, a lubrication-related failure is unlikely. People experiment with different brands and viscosities and miracle additives all the time. Pick a place on the cost and risk curves you're comfortable with, use a quality product, and you'll be OK.

I use Swepco 201 because I can get it really cheaply and urban legend says it is the only thing you should use in a Porsche gear box...

I might be willing to switch if Alpha were around and had a different opinion. That dude knew everything...

Kapitan Krusty says it's unnecessary and I mostly trust his opinion although we do have our differences. 'In The Day' I ran Shell 85W-140 in my six when I was running the Zone Time Trial series and a couple of SD-PCA events at Holtville which is hot, fast, and involves a lot of shifting. Had no issues. This was before I (or most anyone) had heard of Swepco.

But I do a lot of things that are probably unnecessary...

(And I agree Alpha was The World's Foremost Expert. I am beginning to think he has returned - at least in spirit... )

Personally, I don't care what you use for tranny lube.....you can fill it with warm recycled beer iff'n you want.

The gears, bearings, sliders, & whatnot don't care which gear lube you use as long as it is the proper weight, IMO....ah, but the syncros...As a little aside, the syncro rings are coated with Molybdenum. When that wears thru, the syncro is toast, that is the wear limit......look it up in your shop manual.

heck why not fresh beer, like a few pints of Canadian stout( i will bring some down for your tranny).....recycled smells far to rotten...
......
there seems to be no true consenses on this issue

Well, I think everyone can agree that we should use whatever Alpha says...

Alpha has been superseded by another lister. Young, dumb, & fulla cum is not a rarity on the net....in case you haven't noticed.

Sure there is.
No one has suggested that a lubricant meeting the owner's manual specifications will do harm.

Lots of people think they have a better idea and use non-approved lubricants.
Lots of people there are superior lubricants that _do_ meet the manufacturer specifications. Other people think that anything beyond the specification is not necessary.

If you want to experiment in your own car, go for it.
If you think I am going to _recommend_ a product that does not meet the OEM specs -- nope - ain't gonna happen. (Even if I am willing to share anecdotal evidence that I have in fact used other-than-approved products ...)

I suppose I shall have to refer to him as 'the Beta Unit...'

You clever sumbitch.....I admire that.

Could Beta's screen name be pronounced... Goof???

Another choice............Redline!