My new (used) Fordzda Branger has an M5R1 manual. Factory says Merc V ATF. Some Ranger guys are saying it's a big upgrade to use something like Redline's MTL and others say that the synchros will be slower with the thicker fluid.
It made me wonder about the tech behind it... As I'm planning to drain and refill the trans anyway, what is "best?" More importantly, why?
I put redline MTL in my E36 that called for ATF. It transformed the shift feel of the car. I don’t know why or how but ever since it’s worked flawlessly. It seemed to gradually improve over time and got noticeably better after the second fluid change. That stuff is good
Pennzoil synchromesh is also excellent. It brought back a dead second gear synchro in a second crappier E36 I owned for a time.
Wouldn't it depend on what you are doing with the car? E.g. on my track car I use redline MT-90, but I care about not blowing up, and not so much about things like low temp viscosity.
What does viscosity affect (other than the obvious lubing properties)? Time for synchros to match?
I would imagine thicker oil might row like molasses and would obviously waste a wee bit more torques.
I'm not overly worried about destroying anything since I could always just do another drain and fill if the lube I choose does something I don't like, I'm just not keen on spending big bucks for 4 quarts of something special only to recycle it the next week.
I think my real question/shock here is that Redline's MTL is thick stuff. ATF is 10-20w oil, while the MTL is 70-80w. That's a huge difference.
Yeah, I would NOT put mtl in a car that calls for atf.
I'm trying to remember what car I did it on (Fox body mustang I think), but I'm pretty sure the fluid created a grind.
I had heard ATF started being specified because it cut down on the fluids needed at the factory. Don’t know if it’s true or not, though. The Neon guys tend to swear by Pennzoil Synchromesh versus the factory recommended ATF+3/+4. I seem to recall something about the Pennzoil stuff is supposed to be better for the synchros than regular ATF. I think it will be variable from transmission to transmission.
I'm sure each transmission would respond differently to different lubes. I did post a couple threads on Ford forums, but I have yet to find a Ford forum that is populated with real tech-y people. Lots of threads about how to change a headlight bulb, what floormats are the best, or "hey look at my new rimz" but very little real tech.
Pennzoil Syncromesh brought back a dead 2nd gear syncro on my Galant VR4.
I never had any luck with Mobile 1 gear lube. It made every car I've tried it in shift worse. It made my Miata shift bad.
ATF is basically a hydraulic oil/lube.
Manual trans fluid is specifically made so it plays nice with things normally found in manual transmissions such as brass, bronze, synchros, etc.
You will find gear oil and manual trans lubes listed as GL4 and/or GL5.
The GL differential lube rating system has NOTHING to do with manual transmissions... it's specifically about how much wear happens in a hypoid differential.
There is no SAE spec/standard for manual transmissions.
Knowing the above you may think that GL5 is better than GL4... for differentials yes.
The difference is GL5 gear lubes have EP (extreme pressure) additives, USUALLY some amount of sulfur.. which provides additional protection in sliding gears (hypoid).
The problem is these additives attach themselves to yellow metals (bronze or brass, usually used in manual transmission synchros).. and causes them to basically wipe themselves out.
Because of how the 4/5 rating system is... anything that is GL5 rated... will mean it passes GL4 standards. So you'll find some gear lubes with GL4 + GL5 on them. Don't use GL5 in a manual trans to err on the side of safety. There are some that are safe, but short of calling the manufacturer (and even then who knows if you're being given the right info or not), you won't know.
Also note that the gear oil GL-x and the motor oil SM/SN/SL/etc weight ratings are on two completely different scales.
75w90 is equivalent to 10w40. Look at the SAE charts on this page for comparison:
https://wiki.anton-paar.com/en/sae-viscosity-grades/
Motor oils are meant for shorter change intervals and will likely lose their viscosity sooner than a gear oil.
Fun fact: The NV3500 manual trans in 03-06 Wranglers calls for Mopar NV3500 Manual Trans Fluid (doesn't have a viscosity or anything... it's just special fluid for that trans)... the part number that it superceded? Mopar 10w30 synthetic motor oil.
I haven't done enough research on ATF to know the specific differences... but I'd wager to guess that running a thin manual trans lube such as Redline MTL would be an improvement.
FWIW per this:
Mercon V is 7.5cSt at 100C... between a 20w and 25w oil. (note that mm squared per second IS centistokes... it's a direct conversion).
Redline MTL is about 10cSt FWIW... so it's a good difference in weight... but if some use it with success then go for it.
To muddy things up even more my car (Mazda2) specifies 75w80 in the US, but 75w85 and 75w90 in other parts of the world. My car shifts smoother/better with the Ford XTM5QS MTF (75w90) than with Redline MTL (75w80).
And to do so even more... chances are low your trans will ever reach 212F... so since fluids are not tested at any viscosities between stupidly cold and 100C... you'll never know which ones are REALLY thinner/thicker at operating temp. You can make some decent guesses, but that's about it.
I'd highly consider trying just 10W30 oil and see how it feels... it's at least inexpensive and easy to find if it does anything funny. Reality is it's a truck transmission... it's unlikely to care as long as something is in it. 
I certainly cannot match the knowledge above, but I will reinforce something noted: I run a modified T5 in my Corvair (sealed from the diff so it can use different oil). They are speced for ATF originally. A good amount of research from people who know more then me determined Penzoil Synchromesh was the best choice. ATF, as noted, is assumed to be some sort of compromise.
flatlander937 said:ATF is basically a hydraulic oil/lube.
And to do so even more... chances are low your trans will ever reach 212F... so since fluids are not tested at any viscosities between stupidly cold and 100C... you'll never know which ones are REALLY thinner/thicker at operating temp. You can make some decent guesses, but that's about it.
It should also be noted that automatic transmissions are also full of gears and bearings which rarely fail.
Any material data sheet I've ever seen that shows viscosity in centiStokes also shows it at 40c which is a relevant temp for the application.
From my experience having once put generic diff lube in my nissans gearbox, id make sure the GL spec meets up. With gl5 gear lube i drove home fine. Next morning it wouldnt shift without grinding syncros. Did research and parked the truck until i could swap in some gl4 redline MTL which immediately fixed the grinding. Its my go to oil now as long as it matches oem ratings.
I daily a 92 explorer with a m5od-r1hd that I swapped in.iirc the spec is something like 3 quarts.I used 1 quart of lucas transmission fix and the rest in merc v atf. It shifts great. also one may want to consider changing the shifter bushings.
Wow, flatlander. Thank you. In my research last night I had discovered the different weight scales for GL and SAE, but had no idea it was that dramatic a difference. I mean, you pour a bottle of 10w30 and compare it to pouring a bottle of 75w90 in a differential and it certainly seemed like apples to apples. One pours quickly and the other is like honey. I had no idea that the viscosities were effectively the same. Hard to wrap my mind around this stuff.
Busted plug... yup. I'm going to do the shift rail plugs as well. I'm trying to decide if I want to just do bushings, or if I want to do a Core or Hurst shifter instead.
So my trusty google-fu has returned anecdotal stuff about how Royal Purple sucks, Redline is great, Pennzoil Synchromesh is great, and Amsoil doesn't really make the popular list. I'm not married to the idea of using the expensive stuff, but I always wanted to research this and you guys are helping immensely. This particular transmission occasionally seems to be a bit slow to synch. I was trying to blame it on the slave/master, but they don't seem to be the issue. With the extensive maintenance list this truck had from the previous owner, (and with only 88k on it) I'm hoping the problem is that it just has a cheap/incorrect/wasted lube in it.
More on why I originally suspected the slave/master:
Let's say that clutch pedal travel is on a scale from 1 to 10; 1 being all the way to the floor disengaged, and 10 being all the way out/engaged. During all of my operating, the clutch starts to engage at 4, and is fully engaged at 7 (these are random guessed numbers). So, if the clutch is engaged (10) at a stop and I push it in (1) and go for first gear, it takes a bit more effort than I'm used to. Shifts through the rest of the gears take slightly longer than I'm used to with an M5R1. So I did some experimenting. If I sit at a traffic light and leave it in gear with the clutch disengaged (1) and then take off when the light is green, it still engages at 4-7 which tells me that the slave/master is not failing. Also if I disengage the clutch (go from 10 to 1), put it in first with that little extra effort, then take it out of gear for a few seconds (or even a minute) and back in, it slides right with no effort in which tells me the clutch isn't dragging.
This leads me to think it is something internal; either worn synchros or a poorly chosen fluid. Hence why I want to try a better fluid and see if the problem changes/improves.
The hurst shifter sure does look nice, but bushings cost like 12 bucks. Also doing the bushings makes for easy access to fill the trans. When I did mine I threw a piece of moving blanket under the shifter boot which noticeably reduced road noise in the cabin.
On the 4.0 ohv intake manifold gaskets are usually where mystery coolant loss is. The coolant temp gauge is a fancy idiot light. the cts(coolant temp sensor) will go bad and ruin your mpgs. And cleaning the ground lug on the ignition control module tends to solve random misfires.
Curtis said:More on why I originally suspected the slave/master:
Let's say that clutch pedal travel is on a scale from 1 to 10; 1 being all the way to the floor disengaged, and 10 being all the way out/engaged. During all of my operating, the clutch starts to engage at 4, and is fully engaged at 7 (these are random guessed numbers). So, if the clutch is engaged (10) at a stop and I push it in (1) and go for first gear, it takes a bit more effort than I'm used to. Shifts through the rest of the gears take slightly longer than I'm used to with an M5R1. So I did some experimenting. If I sit at a traffic light and leave it in gear with the clutch disengaged (1) and then take off when the light is green, it still engages at 4-7 which tells me that the slave/master is not failing. Also if I disengage the clutch (go from 10 to 1), put it in first with that little extra effort, then take it out of gear for a few seconds (or even a minute) and back in, it slides right with no effort in which tells me the clutch isn't dragging.
This leads me to think it is something internal; either worn synchros or a poorly chosen fluid. Hence why I want to try a better fluid and see if the problem changes/improves.
I drove on a weak slave for yrs. It sounds like the trans is low on fluid and I would bet the rail plugs are gone or at least weepy. a little rtv on the rail plugs and the lucas should get you where you want to be.
I've had excellent lucky with shockproof lite, and add friction modifier is a torsion differential is part of the equation.
Hmm, two testimonies for the Pennzoil stuff bring back dying synchros. I may have to try it in the ratty Miata. 5th gear tends to grind if I don’t double clutch it. Right now, it’s got some expensive redline gear oil in it.
You put redline gear oil, like for the differential, in your miata transmission?
In reply to Toebra :
One of their manual transmission oils. I should have been more specific. Just can’t remember which one.
I've been down this road a good bit...
First, in miata and rx7 trans, the best fluid I have found is the idemitsu fluid. It rocks. Only thing I have found that will keep synchro happy while road racing.
The t5 trans calls for atf. It is fine for the first 4 synchro, but does not work well with the 5th gear on a wc trans. The royal purple was specd to me by the guy that wrote the book on rebuilding these trans. It cleared up a lot of shifting problems and made the trans shift awesome.
As far as the trans in question... I would try to find out if the synchro are yellow metal or a newer material. If they are yellow metal, use the synchromesh.
bustedplug said:I drove on a weak slave for yrs. It sounds like the trans is low on fluid and I would bet the rail plugs are gone or at least weepy. a little rtv on the rail plugs and the lucas should get you where you want to be.
There isn't any leakage coming down the side of the tranny, but it does warrant investigating.
Seems like I read something about a steam cleaning of the truck , but I may be mistaken. In any case, the only problems that I have had out of the m5od were fluid based with the one exception being a worn 3/4 shift fork that would slide out of gear. I think this was caused by riding around with a hand resting on the shifter.
as to the 4wd, the problems I have had, have been electrical either in the 2hi/4hi/4lo actuators' detent bumper thingy or the motor contacts.
for ranger/b-series/explorer stuff I find therangerstation and fordexplorerforums to be my goto for signal/noise ratio.
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