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Posted by: mxhondarider832 Nov 5 2009, 01:45 PM

I have a '74 914 and the transmission is a little leaky and need to change the fluid, the book says to use straight 90w oil but I am having a really tough time finding it so I was wondering if there was a newer substitute that I could use. This is my first 914 and I am struggling a little bit and could use some help thanks

Posted by: underthetire Nov 5 2009, 01:54 PM

OH no, you just poked a pimple. I use 80/90 standard crap now. Had redline$$$ MTL in it once. Shifts better with the cheap stuff. A lot of guys use Sweepco and they will soon respond and tell you where to get it. I think it's up to you how much to spend on the oil.

Posted by: Zundfolge Nov 5 2009, 02:18 PM

I had a harder time finding the 17mm allen wrench locally than I did 90w.

Posted by: SirAndy Nov 5 2009, 02:19 PM

Swepco 201 is expensive and the Cap'n will tell you it's no good but i've been running it for years with very good results.

It made a noticeable improvement in shifting from whatever the PO had used. Transmission oil is not really a "wear" item, which makes it easier to justify the extra expense for Swepco.

I cleaned up and re-sealed my 901 about two years ago and it's still bone dry.
Andy

PS:

Posted by: tat2dphreak Nov 5 2009, 02:54 PM

I'm using Valvoline 85w-90 I think it's a good oil at a good weight and that's what matters.

Posted by: Drums66 Nov 5 2009, 04:27 PM

That's what I use!........put whatever you want in it! as long as
it's expensive! LOL (that's what you say)

Posted by: tod914 Nov 5 2009, 04:35 PM

Just put the Swepco in mine. Shifts much better like Mr. Andy said. Need another spoon in that pot?

Posted by: Mark Henry Nov 5 2009, 04:51 PM

Just use the cheap gear oil and change it once and awhile.

Swepco does have some pretty blue dye in it, so you can't miss it if you have a leak.

Posted by: westgl Nov 7 2009, 12:50 AM

Redline MTL is the old gearoil dont use it

USE: Redline MT90 it is Redlines latest, and works very well, much better than MTL.

my 2cents

Westgl

Posted by: ME733 Nov 7 2009, 04:53 PM

...bottom line is THIS If you have really good sycronizers the expensive trick shit oils (silicone oils, or oils with ptf,s, etc,) will work better than std transmission oils..(for a while)..IF you have an older transmission with unknown sycronizers use good old VALVOLINE transmission oil found in qt bottles at your local auto parts store...80/w/90.....85/w/90. the gear oil as originally equiped was about a 90 wt oil...without any additives......

Posted by: detoxcowboy Nov 7 2009, 04:58 PM

make sure you get your fill plug off first before taking the drain plug off, that way if your fill plug is stripped stuck in there you won't be run dry with no way to fill it.. 80/90

Posted by: Dr Evil Nov 7 2009, 09:14 PM

Um, no.

Use 80w90 GL5 rated oil only. Redline oil is actually contraindicated in our gearboxes (hypoid gears).

Here is something to consider for those of you who are slaves to the colored oils:

The stock oil was 80w90 GL5 since 30 years ago. The stock oil lasted in abused and unabused gear boxes for 30 yrs.

The colored oils have detergent properties that can be good or bad, depending. Detergents keep the dirt and crap that gets into your gear box emulsified so that instead of settling to the bottom and forming a nice sludge that I find 30yrs later, it creates a nice abrasive lubricant that causes things to wear faster. You might do well to put a filter over the vent on the case, but I dont know for sure. All I know is that nothing settles out of the colored oils and that aint natural.

If you use the colored oils, change them often or suffer the abrasive consequences.

Posted by: detoxcowboy Nov 7 2009, 10:18 PM

Listen to the DR. he is the 914 transmission Dr. 80/90 GL5

Posted by: Drums66 Nov 8 2009, 01:37 PM

Maybe??.......whatever type,it works for me(redline) and
I've never had any issue's(20 years)our cars are 30 plus years old

Posted by: Dr Evil Nov 8 2009, 01:48 PM

From the redline website found here:
http://www.redlineoil.com/content/files/tech/MTL%20and%20MT-90%20Tech%20Info.pdf

"GEAR AND SYNCHRONIZER WEAR PROTECTION
Most manufacturers of manual transmissions and
transaxles recommend an 80W or 90W GL-4 lubricant.
GL-5 gears oils which are required in hypoid differentials
are not used in most synchromesh transmissions
because the chemicals used to provide the extreme
pressure protection can be corrosive to synchronizers,
which are commonly made of brass or bronze. Typically,
the use of a GL-5 lubricant in a synchromesh
transmission will shorten the synchronizer life by one
half. The extreme pressure requirements of spur gears
and helical gears found in transmissions are not nearly
as great as found in rear-wheel drive differentials. A
GL-4 lubricant provides adequate protection for most
manual transmissions, unless a unique design
consideration requires the extra protection of a GL-5."

"DIRECTIONS FOR USE
Red Line MTL may be used in transmissions which
recommend 75W, 80W, or 85W GL-4 gear oils, or SAE
30 or 5W/10W30 motor oils. If a 90W GL-4 or SAE 40,
10W40, or 15W40 is required, MT-90 may be used. If the
transmission or transaxle requires an SAE 90 GL-5 gear
oil, then Red Line 75W90NS or 75W140NS Gear Oil
may be used. In transmissions which recommend Dexron
or Mercon fluids we recommend our D4 ATF which is
very similar to the MTL, being a GL-4 Gear Oil also. The
D4 ATF will provide better low-temperature shiftability,
and the MTL would provide better wear protection for
racing use. MTL is not designed for use in rear-wheel
drive differentials. Those generally require a GL-5 lubricant
such as Red Line 75W90 Gear Oil. It is not necessary
to flush the transmission before replacing with MTL.
Remove the drain plug and drain while warm. Seal
compatibility has been designed to be similar to petroleum
lubricants, and leakage should be no greater than
any other oil of comparable viscosity. Being formulated
with extremely stable synthetic basestocks, MTL and
MT-90 will last much longer than conventional petroleum
lubricants. However, we do not recommend extended
drain intervals, since without a filtration system, there is
no way to remove metal shavings other than draining the
lubricant. The regular maintenance intervals are also
recommended to insure that the proper level of the fluid
is maintained."

I have found before that they specifically prohibited use with hypoid gears, but I do not see that here in such plain speak. OUr boxes need GL-5, but they do not have brass or bronze synchros so the wear there is not of concern. We do have such yellow metals with in the gear box, though, and the GL-5 stuff can attack and oxidize the metals so that they are not pretty...but after 30+ years this has not become a failure point or even a perceived failure point.

Posted by: Cap'n Krusty Nov 8 2009, 02:58 PM

I don't recall EVER saying Swepco gear oil is bad, just that it's a waste of money. GL5 is the oil of choice, specified by the factory. What you MUST avoid is any "slippery" additives, as the synchronizers depend on FRICTION to work. Less friction, less effective synchros, more grinding, more dog teeth wear, more frequent (and more expensive) overhauls. As for Redline, I think the good Dr. has covered that very nicely. We have similar issues in Audi quattros. We use GL4 in the transaxles and GL5 in the rear diffs. Synthetic GL4 is specified, and it REALLY makes a difference in the life span of the tranny.

The Cap'n

Posted by: astronomerdave Nov 9 2009, 01:11 AM

So, the people selling components to convert 914s to electric are saying to use Royal Purple. In fact, if you buy an EV conversion kit, 4 qts of Royal Purple are included. Beats me.

Posted by: Drums66 Nov 9 2009, 01:16 PM

Blah Blah Woof Woof..........I go by experience ,you can't believe
everything you read..... did you read my last post(20 years) same gear
oil, people have mind's of their own...I do!

Come with the Drama asshole's!! no more from me on this topic!

Posted by: Dr Evil Nov 9 2009, 01:22 PM

is your problem?

Posted by: astronomerdave Nov 9 2009, 01:32 PM

yep.

just was adding what another group's opinion is. nothing more. hence the "beats me".

Posted by: underthetire Nov 9 2009, 01:38 PM

Did you see my first post? First reply? I told you you poked that pimple.

Posted by: Dr Evil Nov 9 2009, 01:57 PM

So you are saying that people are allowed to be jerks because they disagree with someone else point of view? We have few rules here and calling people "assholes" because they disagree with you violates them.

Posted by: detoxcowboy Nov 9 2009, 02:04 PM

Posted by: Gint Nov 9 2009, 03:11 PM

is with you people lately? I feel like a babysitter. Can you not have a civil conversation without acting like children? We have like 3 or 4 rules. GO READ THEM!

http://www.914world.com/bbs2/index.php?showtopic=65693

Specifically this one:

• Don't call anyone names. Treat other members like your mother taught you - If you can't say something nice, don't say anything at all. No personal attacks.

Those of you that have violated that rule know who you are. Don't make me have to suspend anyone. Frankly I have better things to do.

Posted by: SirAndy Nov 9 2009, 03:26 PM

Listen to the Ginterminator kids ...

Posted by: underthetire Nov 9 2009, 03:44 PM

Funny thing to, Redline MT90 is fairly new. It's not been around for twenty years. I have tried MTL, MT90 and Valvoline 80/90 all in the 914. It works the best with 80/90 Valvoline, less syncro grinding. My Toyota truck that I put a brand new transmission in shifted WAY better with the MTL. I think it really depends on the transmission.

Now, can we just get along please. No more cause it's just not fun.

Posted by: wobbletop Nov 9 2009, 03:48 PM

When I visited the local Swepco guy, he showed me a demonstration like this one:

http://contimp.com/SWEPCO%20201%20Demo%20320/SWEPCO%20201%20Demo%20320.html

Comments?

Posted by: steuspeed Dec 18 2011, 10:30 PM

Dr. Evil. So I should be running this Red Line non synthetic GL5 gear oil 75W-90? Sounds like the stuff I need. Or maybe just run good old Valvoline like underthetire says.

http://www.redlineoil.com/product.aspx?pid=47&pcid=7

Posted by: Richard Casto Dec 19 2011, 09:58 AM

Yes and no. Transmission oil doesn't live as hard of a life as engine oil, but I would put it firmly in the "wear item" or "needs to be replaced" category. Stuff can get inside (such as via the breather vent) and periodic replacement can flush that stuff out. Also, the oils have additives (particular such as the EP - Extreme Pressure) that do not last indefinitely. Not that you said it, my concern is I don't want new owners to think transmission fluid is a "never change" item. It does have a service schedule.


I know why you are saying this, can almost agree, but don't agree. Redline does have a GL-5 transmission fluid that should be fine in our transmission. I haven't used it, so I can't say how well it works. Even your other post above with the text from the Redline site does says which of their fluids to use in our transmission.

What concerns me about Redline is that it's really easy to buy the wrong fluid from them. I see lots of comments about "Redline MT Fluid". Are they using "MT" as a generic term for "Manual Transmission" fluid or the specific "MT/MTL" product line from Redline? The specific "MT/MTL" line of fluids from Redline is GL-4 ("4" not "5") and should NOT be used in a 901/914 transmission. As you say above it is not GL-5 and is not compatible with hypoid designs. So we can agree on that. Specifically the following from Redline should NOT be used in a 901/914

* Red Line MT-90 GL-4 (Not GL-5 spec)
* Red Line MT-80 GL-4 (Not GL-5 spec)
* Red Line MTL GL-4 (Not GL-5 spec)

But Redline does have two GL-5 products. BUT of their two GL-5 fluids, one has a lot of friction modifiers and even on their site says that it should NOT be used in transaxles (combo transmission with synchros and a differential). That due to the friction modifiers you may experience bad shift quality. In short that fluid should also NOT be used in a 901/914 transmission. The second one however does look to fit the bill. Basically you really have to read all of the fine print to zero in on that one single product out of a small sea of manual transmission fluids from them. That one Redline fluid that should work is "75W90 NS GL-5 Gear Oil". The three things to note are...

* "75W90". The viscosity is not 80W90, but probably is fine
* "NS". This is the version that has less friction modifiers so it is more compatible with our synchro design.
* "GL-5". It is GL-5 spec and works with hypoid gears.

Here is a direct link on thier site...

http://www.redlineoil.com/product.aspx?pid=47&pcid=7

Now because it is so easy to buy the wrong thing from them I can understand the "Don't buy Redline" stance. Even then, someone may use the right stuff from them and still report problems (such as the other thread in which Swepco is not working well for one guy), or it might work great for them. As always, your mileage may vary!

On top of all of that, I put Redline in the "boutique" category just like Swepco. Which again may or may not add any real value. I probably wouldn't buy it personally and would just buy good quality GL-5 dino oil from one of the regular mainstream vendors (Valvoline, Castrol, etc.).

Lastly, here is my article on transmission fluid...

http://www.blueskymotorsports.com/index.php?option=com_content&view=article&id=16&Itemid=6

Richard

Posted by: Richard Casto Dec 19 2011, 10:00 AM

You link is broken. So I can't comment!

Richard

Posted by: gothspeed Dec 19 2011, 03:05 PM

I agree with Dr E's logic for GL5 ................ and that redline oil on your link looks like an updated version of it ............ ............ I would use it !!

Posted by: Dr Evil Dec 19 2011, 06:34 PM

Use what you want. I already posted my experience in several places, and in the 31 pages of notes, that you should read, that comes with a TOC. Tranz oil is absolutely a wear item; Heat and dirt.

Posted by: Drums66 Dec 20 2011, 05:00 PM

.........Read my other post....mr discredit (Redline period)

Posted by: SirAndy Dec 21 2011, 02:56 PM

Chemically speaking, it doesn't get hot enough to start breaking down. Thus my comment about not being a "wear" item.

Never did i say anything along the lines that it doesn't get dirty or that it should never ever be replaced.

However, i do disagree with those who claim that one must replace the transmission oil at similar (or close to) intervals as engine oil.

And yes, i still run Swepco, and yes, i'm still happy with the shifting. YMMV.

Posted by: Mark Henry Dec 21 2011, 06:03 PM

Oil preference is almost as bad as politics and religion.
If you have already bought swepco just run it. If you like it and are willing to pay the price just do it.

I have some 201 and what I've been doing (on my VW Golf and bus) is filling it with 2L of cheap stuff and topping it up with the 201. Gives it the pretty blue colour that's easy to tell from engine oil if you have a leak.
One pint (500ml) mixed in should do the job.

I'm going change the oil every so often, more likely for age than mileage.

Posted by: Steve Dec 21 2011, 06:19 PM

I'm confused... if the oil doesn't get hot enough to start breaking down, then why does Porsche put external oil coolers on there transmissions, including the 915?

Posted by: SirAndy Dec 21 2011, 06:23 PM

Of course you want to keep your transmission oil cool. I never said anything otherwise. I never said you don't benefit for an oil cooler.

But there's a difference between chemically braking the bond of molecules (very bad) and oil thinning out due to heat (bad enough).

Posted by: Dr Evil Dec 21 2011, 06:24 PM

I guess we will have to agree to disagree. At what temp would you consider oil to be a wear item? Chemically speaking, it is breaking down inside the bottle. It is degrading the moment it is created. Heat accelerates this, more heat even faster, but it is not necessary. Since the oil is less heated than engine oil, it need not be replaced other than at the 10Kmi interval recommended by the engineers at Porsche. I recommend Swepco be changed more often as it still gets dirt and gear crap in it, but that it keeps it in solution so that it may interact with the other parts of your gear box on a regular basis. Will this be witnessed in the short term? No way, long term this will lead to $$$.

Mark, you are on the ball. This seems to be like a religion or politics discussion.

Posted by: Steve Dec 21 2011, 06:28 PM

Thank you for the clarification!!

It's funny why Porsche put external oil coolers on 3.2 915 trans in Europe but not in the states. You think it would be generally hotter over here than in most parts of Europe.

Posted by: SirAndy Dec 21 2011, 06:30 PM

Speed limit (or lack thereof). My guess is the cars see a lot more high speed driving in Europe compared to the US.

Posted by: Drums66 Dec 21 2011, 07:26 PM

.......Autobahn helps

Posted by: Richard Casto Dec 21 2011, 09:07 PM

Regarding heat... In another thread elsewhere it was mentioned (I think by Jake Raby) about the percentage of power loss via a 901 transmission. If I remember correctly it was above 20% which is high, but he had the dyno numbers to prove it. My point is that you have to remember that all of that energy is being converted into heat and noise with most probably being heat. I wouldn't be surprised if the 915 has similar friction losses and ultimate potential for heat generation. And the more power you put in, the hotter is will get. At some point cooling is needed.

Oil is and will always be a religious discussion. And while there is plenty of "opinion" here, I think there is also plenty of "fact" as well. All fluids in a car live a tough life. Some worse than others. At a minimum the factory put in a service schedule for a reason and I suspect the primary reason was to not just sell you more oil at service visits. And about the best empirical data we have is that regular old "dino" or "mineral" oil has worked well for decades in these transmissions.

Otherwise, there is no need (for me) to rehash what has already been said!

Richard

Posted by: Steve Dec 26 2011, 11:04 AM

I need to toss some old oils in the garage, but I stumbled across some Mobile 1 synthetic 75-90 GL-5 oil in the garage. Is synthetic GL-5 bad? Should I toss it? It's probably been sitting on the shelf for 15 years anyway.

Posted by: steuspeed Dec 26 2011, 02:06 PM

I'm going back to NON synthetic ASAP! I can barely get it into first gear with SWEPCO. I have to wait for the revs to drop way down getting into second now otherwise the teeth zip because the oil is so slick. It's not the typical grind.

Posted by: scott_in_nh Dec 26 2011, 08:36 PM

I had shifting that was about the same as the OP's.

So I drained the swepco and put in Valvolene 80w-90.

I only had time for about a 10 mile drive, but it seems that 3rd-5th shifts are about the same, 2nd is smoother and grind free so far and 1st slides in much easier.

I'll report again after a longer drive or after some stop and go driving in traffic.

Posted by: steuspeed Dec 30 2011, 01:29 AM

I could not find Valvoline without the Limited Slip tag on the bottle, so went with CarQuest 80W90 GL5 rated Hypoid gear Oil. $15.97 a gal and shifting way better than SWEPCO.

Posted by: 442nd914s Dec 18 2012, 05:35 PM

If I can just ask a simple question. And only because Im a newbee. There are 2 plugs on the right side of the tranny. Top one is the FILL and the bottom one is the drain? Is that correct? How many quarts will I need to service it properly.

Posted by: Dr Evil Dec 18 2012, 06:55 PM

Hey Dude,

We all have to learn some time. You are correct about the plugs. Use approx 3L of 80w90 GL5 oil and fill until the oil starts to come out of the fill plug.

Posted by: steuspeed Jan 2 2013, 04:23 PM

Make sure you can get both plugs out before you drain it. I think the spec is about 15ftlbs, and I had to use a breaker bar to get the drain plug off mine. Some jerk at Jiffy Lube probably used his impact wrench on it. Go with 80W90 GL5 rated Hypoid gear Oil. If it says HYPOID you have the right stuff. If it says synthetic or for limited slip take a pass. Stay away from SWEPCO. It's not designed for old worn transmissions.

Posted by: Dr Evil Jan 2 2013, 04:57 PM

ALWAYS take the FILL plug out first. If you drain it and then find out that you can not fill it, you will be bummed.

Posted by: mrbubblehead Jan 2 2013, 08:30 PM

after finding out how much it costs for new gearbox parts, i am seriously considering adding a pump, filter, and cooler to my trans...

Posted by: Dr Evil Jan 3 2013, 05:00 PM

No amount of oil cooling will fix poor shifting technique or a maladjusted tranz.

Posted by: Steve73 May 27 2013, 01:52 PM

How about SuperTech 80w-90 GL-5 from......Wal-Mart.

Already have some to put in my Bug

(Don't beat me!)

Posted by: Randal May 27 2013, 02:01 PM

Swepco 201 is great. Like Andy I've been using it for years.

Rich Bontempi (High Performance House) told me about it an put the first refill in my transmission. FUI Rich is also a well know racer and car builder.

Probably the best test of transmission fluid would be the guys running longer events. There are a bunch of people running longer track sessions and their experience would be invaluable.

Posted by: 396 May 27 2013, 04:52 PM

Like its been said...it's like religion. I've used M1 trans oil, Swepco and the local FLAPS
I've even used a cocktail of M1 with Swepco..I know Swepco cost more but like some have mentioned, if you track your car, why not simply put the one product that saved the 934/935's gear boxes during Porsches finest hr.
.02$

Posted by: d962r Jun 25 2013, 05:41 PM

So has anyone tried any of the Lucas Oil additives?

Posted by: Dave_Darling Jun 25 2013, 06:31 PM

Make sure the car is at least close to level when you do this... Don't ask how I know.

--DD

Posted by: monkeyboy Jun 26 2013, 12:10 PM

I don't use the additives, but I have used their transmission oil with good results.

Posted by: second wind Jan 4 2023, 02:29 AM

Ok....is it just me or is this thread REALLY CONFUSING??? I believe a 914 is supposed to use conventional GL4 tranny oil....how did it get to this confused controversy that allows GL5? I am getting a headache over all of this double talk.....someone please tell the truth....thank you,
gg

Posted by: Front yard mechanic Jan 4 2023, 06:16 AM

Being a ten year old thread you might as well start it up again! I use chicken grease in mine it clucks less from first to second

Posted by: zoomCat Jan 4 2023, 11:39 AM

The owners manual in my car specifies 90 weight MIL 2105 A gear lube. That translates roughly to GL4 in modern parlance, I suspect it may have been the highest grade gear oil commonly available in the late 60s but I haven’t been able to find much discussion of the historical development of the standards. Note that the factory also specified 12,000 mile change intervals.

The difference between GL4 and GL5 is the amount of EP (extreme pressure) protection, usually provided by phosphorous/sulfur compounds that bind to wear surfaces and sacrifice themselves to protect the underlying parts. The anti wear compound is actually harder than the brass commonly used in synchronizers, and binds to that surface with enough tenacity that it will compromise the synchro; GL5 has enough EP additives that is it counter indicated for brass synchros. GL5 is typically rated only for unsynchronized transmissions, but Porsche used steel synchros so this shouldn’t be an issue for the 901 used in 914s. The geometry of the differential should benefit from the increased EP protection.

Shifting quality is largely a function of viscosity and any friction modifiers, whether deviations from the original specs improve anything are a different discussion.

Personally I’m going to use 80w90 GL5, nothing exotic, and change at 12k (or earlier if I have the whim). Others will have varying opinions, I’m sure, and may have more specifics.

Posted by: emerygt350 Jan 4 2023, 11:58 AM

I believe Dr. Evil said plain old nothing fancy 80/90w GL5 is what you want with these transmissions. 13 years ago.

Posted by: 914043 Jan 4 2023, 01:17 PM

As always I use amsoil products,they specify GL5. Now the reasons synthethic is so much better than conventional oil go to their website click on Performance Test Archive scroll down to 75W-90 synthethic vs petroleum gear oil testing and decide for yourself.

Posted by: Steve Jan 5 2023, 12:00 PM

Last I read synthetic is too slippery for our synchro's and not to use it. Just standard 90w gear oil.

Posted by: second wind Jan 6 2023, 01:16 PM

Here is a good question....will adding Lucas Oil Stabilizer alter the GL4 properties that I am searching for? Will it make the tranny oil too slippery or what exactly will it do ?
Thank you,
gg

Posted by: Geezer914 Jan 6 2023, 05:25 PM

Kendall MS-NP Hypoid gear oil 80-90W.

Posted by: Superhawk996 Jan 6 2023, 09:37 PM

@‘second wind’

No snake oil required. Oil OEMs spend a lot of time and testing to ensure it meets GL standards - no need to modify what they have done.

You want GL-5 for the hypoid differential in our transaxles (per Dr Evil and per standard engineering practice for hypoid differential). The synchros in a 901 transaxle are steel - not brass so don’t worry about the nuances about brass synchros needing GL-4.

Posted by: Brian Fuerbach Jan 6 2023, 09:52 PM

I have to agree. After trying a few brands including Valvoline, I found Kendall to provide the best shifting.