manual transmission oil

T

Tiajaunatoad

Member
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2012 MS3
I was thinking about changing the trans fluid in my 5 speed manual tranny and going back with BG synthetic fluid. Has anyone here ever used the BG fluid? It is 75w140 full synthetic gear oil. According to alldata, its supposed to take 75w90 gear oil. I do mostly highway driving at 70-75mph and live in a warm part of the country ( summer temps avg high 90s). I wanted to know what you guys think and was looking for some feedback. Thanks.
 
Use the 75w90 your sposed to. Brand is up to you a lot of people use mobile 1 or royal purple personally I'm a royal purple fan. Up to you
 
Wouldn't hurt to be different I learned today that hondas use 10w40 motor oil for their trans because gear oil is too thick
 
I don't think gear oil and motor oil weights are equivalent, i.e. 10w40 gear oil won't have the same viscosity as an SAE 10w40 motor oil.

Also, I dunno if anyone can clarify this for me, but my local dealer (can't remember if it was weber or sundance) told me that they just use regular ATF in the protege manual tranny.
 
tweety2300 said:
Wouldn't hurt to be different I learned today that hondas use 10w40 motor oil for their trans because gear oil is too thick
Click to expand...
I have friend that put a clutch in his older civic( mid 80s I think) and
killed his tranny by putting heavy gear oil in it when he should have used either 10w40 or 20w50 motor oil. That said, the reason I want to go with the BG 75w140 is I can get free from work. I have used the royal purple in a 97 5speed altima I had and thought it performed well. Not that I'm cheap but if the BG oil would work i'd like to save the 7or8 bucks a quart that I'd have to pay for royal purple.
 
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Ya royal purple is expensive but for a once every year or 2 thing spend the extra money you get what you pay for well sometimes you pay way more if you go cheap like a transmission... also I believe atf is extremely bad for. Syncros. Or something like that but just put what your sposed to in it and be safe unless your rich then experiment :)
 
Well I'm not rich and I don't feel like being a guinea pig so I guess I'll go with the royal purple. Thanks for your input.
 
I can't remember the numbers off the top of my head...but I believe our gearbox's need GL4 75w 90 gear oil...I'm saying this because the Mobil 1 gear oil at most parts stores is GL5...not 4...and GL5 has sulfur additives and other things that are not good for the type of syncro's our transaxles have...I had a probe GT before my P5 (which had a similar Taxle), installed Mobil 1 gear oil...had no idea what any of that GL stuff meant...and ended up losing 5th gear just a week later...I'm sure it was close to going anyway, so it might have been coincidence...but after some research I found out about the different GL ratings...

Royal Purple and Red Line (as well as many others) do make GL4 gear oils...I don't know if Mobil 1 does or not, I just know every time I see it I check the back and its GL5...

I have had Red Line MTX-90 or whatever it was in mine for a while, and its been great...speaking of which though I should change it, its been 75k miles or so...
 
Did you notice any improvements (better fuel mileage or shift quality) with the synthetic oil over the conventional oil? I have a stock engine and tranny with 250k+ miles on it. I've been using mobile 1 in the engine mainly so I won't have to change the oil as often (can avg 800 -1000 miles a week) and was hoping that with synthetic oil in the tranny I might improve my mpg some.
 
As reported by Instalshield 2, I read yrs ago of sulfur additives in GL5 that quickly deteriorate "yellow metal" synchro parts.
I spent months looking for GL4's to little avail. I believe Amsoil, Redline, Royal Purple have them now.
There wasn't a single Transmission tech, dealer, or Mazda Inc, that had a clue about any of this.

I finally found this info comparing several.
http://www.syntheticwarehouse.com/brochures/g2457_gearlube_study.pdf

The study is paid for by Amsoil, but it does give decent info on many brands, and does address the GL5 sulfur issue, along w/ a whole lot of other interesting data.

I would have gone w/ Amsoil, but I couldn't find a dealer easily. Finally went w/ Valvoline 80w90 synth. There was some noticeable smoother shifting.

Interesting: Mazda Inc reported back to me to never change 5-speed oil unless there was a problem. Stupid response IMO.
 
I finally decided to go with the royal purple. Would have gone with mobile 1 but the parts store I was at only had 2 qts. They did have enough of the penzoil syncromesh but when I looked at the bottle I couldn't find the actual oil weight on it. The royal purple was alot more than I wanted to spend but I was dead set on getting this done when I started it. I've had it in now for about a week and it seems to be working well. At first i didn't notice much difference in shift quality but the more I drive it the smoother it seems to shift. That may just $18 a qt placebo effect :)
 
I put the mobile 1 stuff in (around $10 a bottle on sale at advanced auto parts). I have read that the royal purple/redline/amsoil stuff use a grade 4 synthetic and the mobile 1 only uses a grade 3? but 10 bucks a bottle sounded a lot better than 18 a pop for me so i went with the mobile 1 and after doing the fluid change and greasing the transmission linkage under the car i have to say its night and day difference when shifting. I'm at around 95k miles and I'm the 2nd owner so I'm not sure if the gear oil has ever been changed?
 
Does anyone know is this something that can be changed in ur driveway? I took a look and noticed it looked like there was just a small filler plug on top and saw the drain plug on the bottom.
 
That's where I do mine. You'll just need either a funnel with a hose, a pump or better yet a suction gun to put in the fresh gear oil. It's a low RPM job.
 
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