Not sure why Jeff switched from Redline to SM.. perhaps he went to SM to get better synchro operation / faster shifts.
Clint
If I remember correctly, the MT90/MTL mix was a bit notchy. Not hard to shift or anything, and the switch to SM seemed like a reasonable lube to try. The shifting with SM was great, but every time I drained the trans, which was frequently because of clutch and engine problems, the fluid had more metallic color contamination than I felt comfortable with. The switch to Mobil 1 10W/30 has reduced the visible contamination level based on draining the trans at about 2500 miles, a much longer interval than with SM. The shifting with 10W/30 is the same as SM except for being a bit stiffer on cold starts for about a mile, before the engine has come to temperature, so it isn't even a concern.
... The synchros in a few of the early stock transmissions were a crappy scintered bronze material, and literally wear themselves out no matter what fluid is used. Later transmissions use a real brass syncro ring, which is an upgrade for the earlier transmissions. ...
DSM and 3S transmissions use the same type syncrho rings and gears, as do most other transmissions. There is NOTHING special about a 3S tranny- it is simply a Getrag built AWD transmission.
I am not taking sides in the gear oil issue. But 3r tech's words might carry a little more weight if he actually knew a bit more about our transaxles. Both of his statements above are inacccurate.
All of our Getrag synchro rings (and cones and sleeves and hubs) are steel except for the reverse ring. 1st - 4th rings are coated on the friction surfaces.
Only the DSM F5M33 is similar to a 3S transaxle, and that is used on the 3S FWD (an MMC-built transaxle).
For the DSM MMC AWD model, only the synchro for 2nd is a dual cone design. In the Getrag, 1st and 2nd synchros are dual cone.
The synchro key retention is an entirely different design in the MMC transaxles.
The DSM MMC AWD center diff is an entirely different design.
As far as "a synchro is a synchro" that is nonsense. It is hard to believe that all transmission manufacturers use the same friction coating on rings. But if they do, I'll retract this comment.
I don't doubt that 3r tech has witnessed DSM MMC transaxles in great shape after abuse with a particular oil in them. But I put as much faith in that as someone telling me their Mustang or Corvette transmission survived abuse great after using brand X oil.
The DSM transaxle is a MMC transaxle. The 3S is a Getrag transaxle. Two different critters (of course, some parts and designs are similar, as are some parts in all manual transmissions).
I for one want to hear reports about oil use in our Getrag transaxles, not some other manufacturer's.
If I remember correctly, the MT90/MTL mix was a bit notchy. Not hard to shift or anything, and the switch to SM seemed like a reasonable lube to try. The shifting with SM was great, but every time I drained the trans, which was frequently because of clutch and engine problems, the fluid had more metallic color contamination than I felt comfortable with. The switch to Mobil 1 10W/30 has reduced the visible contamination level based on draining the trans at about 2500 miles, a much longer interval than with SM. The shifting with 10W/30 is the same as SM except for being a bit stiffer on cold starts for about a mile, before the engine has come to temperature, so it isn't even a concern.
Jeff
Still waiting to hear back from Kormex about the EP protection of Mobile 1 10W/30 versus a real GL-4 lube.
Appreciate your real-life experience using Mobile 1 10W/30 versus SM. No worries from me about cold weather shifting. Good reminder that the rest of the car needs some time to warm up before getting on it.
What are you running in your xfer case / diff?
Clint
__________________
1991 Stealth RT/TT - Firestorm Red - 193K Miles / Original Owner
Maint: Castrol 10W40 / Mitsu Filter / Rislone
Replaced: 2X clutch / 3X brakes / 2X front rotors / 2X ABS HU / 1X NGK Plugs / 1X Ball joints / 2X Antenna mast / 1X Active exhaust cable / 1X Windshield / 1X Fuel FIlter / 1X Struts / 1X rear rotors / 1X Front Head / VSS / 1X rear wheel bearings / 1X Transfer case (warranty) / 1x Tie rod end (drivers side)
Overhauled: Starter, IAC, BISS, CV Boots
Upgrade: SilverStar Headlights / ebay "Xenon" Fog Bulbs (no more yellow!)
A/F Gauge / MAP - Electronic Boost Logging / MMCd Data Logger
Pending Projects: Steering Rack
Shockproof Heavy in both. Since I also believe that oil analysis has value, I will send a sample from the trans this time when it is drained.
Jeff
I do not believe that my differential oil has ever been changed. (175K miles) Transmission / xfer case oil was replaced when the dealer changed the first clutch but that was ~100K miles ago. I check the level / condition every year but have never changed the gear oils until now.
I tend to be old school when it comes to gear oil. Barring any contamination, gear oil can be good-for-life but I am inclined to upgrade now to better synthetic gear fluids. (Good for another 100K miles!)
I am not taking sides in the gear oil issue. But 3r tech's words might carry a little more weight if he actually knew a bit more about our transaxles. Both of his statements above are inacccurate.
Actually your right, I was mistaken about the synchro rings, but then I get to see so many gearboxes(Porsche, Corvette, Viper, etc) apart I tend tolose track unless I have it in my hands. No matter what though, Redline will do the job, for longer, and with better wear than BG.
Since your in the area I invite you to swing by the shop sometime and take a look around-
im thinking ill send my syncromesh out for a test(i can baseline and then send later), i only have about 20 miles on a fresh SM install so far.
Tranny has 120k on it, 2nd gear syncro replaced at 100k, was drained fully and cleaned. 3rd gear works(original owner complained of grinding), new clutch, new clutch assists. No grinding but i think the lock spring is missing) since i dont get a "solid" click when i shift into 3rd.
Then switch to another oil and send it out.
how many miles? say 1500 per test(street driving, mild traffic, some highway) is enough to get a result?
im thinking ill send my syncromesh out for a test(i can baseline and then send later), i only have about 20 miles on a fresh SM install so far.
Tranny has 120k on it, 2nd gear syncro replaced at 100k, was drained fully and cleaned. 3rd gear works(original owner complained of grinding), new clutch, new clutch assists. No grinding but i think the lock spring is missing) since i dont get a "solid" click when i shift into 3rd.
Then switch to another oil and send it out.
how many miles? say 1500 per test(street driving, mild traffic, some highway) is enough to get a result?
Sounds like good methodology. Baseline of oil versus sample at 1500 miles should net valid data. With no filtering in the tranny, anything that wears off the gears/synchros will end up in the oil.
The only thing I would suggest is that you take the sample immediately after driving so you have a representative sample. (Let 1/2 of the fluid drain and then take the sample. Same drill for accurate engine oil testing.)
EDIT: Happy to split the cost of the synchrmesh baseline with you. (Are you using blackstone or some other lab?)
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Re: GM Synchromesh : Long term effect on tranny
Re: GM Synchromesh : Long term effect on tranny
