GM Synchromesh on non GM-Vehicles?

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349
Location
Quebec, Canada
As most of you know, I drive a 5spd. Mazda Protege 1996. Anyway, my shifting turns sour everytime the tranny is up to full operating temps. I've been an ex-member of Club DSM a while back, and some of them use GM Synchromesh in replacement to what should be 75W90. My Protege also calls for 75W90, and I was thinking of using GM Synchromesh. Am I asking for a blown tranny with this, guys? BTW, GM does not specify the SAE grade of GM Synchromesh. Thanks-a-bunch, Oz
 
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3,346
Location
Clarksville, Tennessee
quote:
Originally posted by The_Oz: As most of you know, I drive a 5spd. Mazda Protege 1996. Anyway, my shifting turns sour everytime the tranny is up to full operating temps. I've been an ex-member of Club DSM a while back, and some of them use GM Synchromesh in replacement to what should be 75W90. My Protege also calls for 75W90, and I was thinking of using GM Synchromesh. Am I asking for a blown tranny with this, guys? BTW, GM does not specify the SAE grade of GM Synchromesh. Thanks-a-bunch, Oz
From what I understand the syncromesh is 5w30 motor oil, actually that is what Amsoil recommends to a direct replacement for that. If I were you I would maybe look at using a heavier Gear lube if that is what your car calls for. It sounds like your transmission warms up and then shifts crappy, this would indicate that the fluid is becomming too thin. I have done with with my BMW motorcycle. It calls for a 90wt gear lube in the trans. I run a 75w140 and the shifting is much improved. What I experienced before, with a 75w90, is that it shifted great when it was cold, but when it warmed up, espcially on hot days, it would shift really bad. I put the 75w140 in and now it shifts great cold or hot.
 

The_Oz

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349
Location
Quebec, Canada
msparks, I haven't forgotten about your email. In regards with Synchromesh, Thanks. Just curious though, don't you think 140wt is a tad too thick for a tranny requiring 75W90? Come to think of it though, it might offer better film lubrication [Confused] Is this going to cause synchro problems? I can easily attain 75W140. What about mixing 2qts. of 75W90 and 1qt. of GM Synchromesh? Thanks, Oz
 
Messages
3,346
Location
Clarksville, Tennessee
quote:
Originally posted by The_Oz: msparks, I haven't forgotten about your email. In regards with Synchromesh, Thanks. Just curious though, don't you think 140wt is a tad too thick for a tranny requiring 75W90? Come to think of it though, it might offer better film lubrication [Confused] Is this going to cause synchro problems? I can easily attain 75W140. What about mixing 2qts. of 75W90 and 1qt. of GM Synchromesh? Thanks, Oz
Both 75w90 and 75w140 are basically the same thickness at room temp, but as the fluid gets heated the w90 thins out more thand the 140. I believe that the 140 has a higher shock load too. Which might have a better cushoning effect on the gears. Another think you migh think of is to use a synthetic 75w90. If you are using a conventional now. What would happen is that synthetic would run cooler after all is warmed up. Thus would act like a thicker fluid. My suggestion would be to use a syntheic 75w90 first. Then if it still shifts like crap when it is hot go to the 75w140. That way you won't be losing out. If it runs fine with the synthetic 75w90. Just stay with it. If it still shifts poorly, switch it out. Make sense? This is exactly what I did on my BMW. I tried the synthetic 75w90 first, made some difference, but I still didn't like it. Went with the 140 and does much better. But only you will know in your exact situation. [ August 09, 2002, 09:29 AM: Message edited by: msparks ]
 
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5,069
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Saratoga, NY
How much is a quart of the GM fluid? For $8 U.S. per quart you could use Red Line MT-90 which is an excellent fluid for synchromesh gearboxes and (I believe) is the correct 75W90 weight to boot. [Smile] --- Bror Jace
 
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5,069
Location
Saratoga, NY
Oz, Canada is still North America and I can't imagine one of these three (if not all of them) will ship to Canada: www.auto-oil.com www.manhonda.com www.myoilshop.com All of these places carry Red Line products. Last I looked, though, the Honda dealership only carried a limited number of fluids. If you want a really good oil for your Mazda's tranny, I think you ought to put up with the inconvenience of dealing with mail order. Face it, you're indeed lucky if the 'good stuff' is sitting on the shelf of a dealer near you. [Wink] --- Bror Jace
 

The_Oz

Thread starter
Messages
349
Location
Quebec, Canada
Bror Jace -> I wouldn't even think twice to use Redline MTL. Unfortunately, Redline is hard to acquire here. msparks -> My bad, it's 85W140 rather than 75W90. Either way, there are no real Synthetics available here. Only Castrol Syntec 75W90, Quaker State 75W90, & Motomaster Synthetic 75W90. I'll give them a try anyway and see how it goes. Maybe after winter I'll try AMSOIL 75W90. Regards, Oz
 

The_Oz

Thread starter
Messages
349
Location
Quebec, Canada
ACK!! Stupid drain bolt decides to be in the size where my socket set does not cover [Mad] Anyway, thanks for the info guys! I've taken msparks first suggestion - buy a synthetic. However, msparks, I've bought a cheap synthetic for the time being - well I'm not sure if you call $9CDN per litre cheap. Anyway, we'll see how that holds out. Also, it would've been no use switching to either AMSOIL or Redline since I the drain/filler bolt is only for topping up the tranny case - not draining it completely. So off to Mazda I go for an expensive service manual to check my suspicions for some things. Bror, somehow I missed the fact that Redline MT-80W90 is like 5W30. How is this possible? If so, then using GM Synchromesh (which msparks stated as 5W30) shouldn't be a problem for my Mazda....please confirm [Smile] Thanks-a-bunch guys, Oz P.S. I'll probably change the tranny oil after 10000km, but I need to know how to properly drain most of it out first.
 
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5,069
Location
Saratoga, NY
Oz, Red Line MTL (which is what I use) is a 70W80 or a 75W85 ... something like that. It is very thin ... and pours quite easily. MT-90 is a bit thicker (I think 75W90) but you might want to check Red Line's site. --- Bror Jace
 
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