Gear Oil Recommendation

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BironDanmum

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Hi folks, first post here.

I have a 1999 ZX2 Escort S/R. Previous owner used ATF (Mercon) in the manual transmission. It has the Mazda G5M transmission with the brass synchros.

I've heard great things about the Pennzoil Synchromesh and so that's what went in to the recent drain and fill. Within almost an instant, the gears got really notchy, and you pretty much have to slam it into fourth to get it to shift properly. Otherwise, it just feels like you're trying to shift a hotdog through wet cement.

So after doing further research, I found I'm not the only ZX2 owner who switched to Synchromesh and had this same issue. Two alternatives that I've come across are the Redline MTL and MT90, and also the Royal Purple Synchromax. It seems like a very popular fill is 1qt MTL and 2 qts MT90.

So from the folks familiar with this transmission (or any MTX with yellow metal), would you go for the RP or the RL?
 
Your in Columbus, OH. Go to Jim Keim Ford and ask for Motorcraft XT-M5-QS fluid. It's a
German made, true PAO synthetic. Research it and you'll see it's the favorite among Mazda Miata owners.
It's in my VW GTI and has has been on that same fluid for 48K now. Going 38 MPH in first gear and quickly
shifting to yes, 6th gear results in no synchro grinding.
 
Originally Posted By: skyactiv
Your in Columbus, OH. Go to Jim Keim Ford and ask for Motorcraft XT-M5-QS fluid. It's a
German made, true PAO synthetic. Research it and you'll see it's the favorite among Mazda Miata owners.
It's in my VW GTI and has has been on that same fluid for 48K now. Going 38 MPH in first gear and quickly
shifting to yes, 6th gear results in no synchro grinding.


I thought about the Motorcraft, but I was wondering if it was worth the extra price. I'll keep that in mind.
 
Originally Posted By: barkingspider
Super tech 75w90


The ST, like the Valvoline and most other standard gear oils are spec'd for GL5. You're not supposed to use GL5 spec'd fluid in a GL4-spec'd MTX with soft yellow synchronizers.
 
Originally Posted By: aquariuscsm
Your manual transmission specs Mercon atf from the oem. Go back to the spec'd atf. Here's what Amsoil recommends:

http://www.amsoil.com/shop/by-product/tr.../?code=OTFQT-EA

http://www.amsoil.com/shop/by-product/tr.../?code=ATFQT-EA



Actually the OEM specs ATF or GL-4 75w90 weight "for more extreme conditions such as towing." Since this vehicle sees a lot of track time I want something a little more protective than the ATF.

It's funny- the Mazdas that came with this transmission were factory filled with gear oil, while the Fords that came with this transmission were filled with ATF. The Mazdas were renowned for their smooth shifting while the Fords have always had a reputation for hard shifts.
 
I'd get the Red Line over Royal purple as it is a true GL-4 not just a GL-4 compatible GL-5 like the Royal Purple. No need for the extreme pressure additives in the Royal Purple that might adversely effect the way your synchros work. I use MT-90 in my Toyota manual transmission and it works great. I wouldn't mix it with the MTL.
 
Last edited:
Brad Penn is stating the opposite regarding friction modifiers on synchronized transmissions saying it can interfere with proper synchronizer performance. Please explain!
 
Quote:
I'd get the Red Line over Royal purple as it is a true GL-4 not just a GL-4 compatible GL-5 like the Royal Purple. No need for the extreme pressure additives in the Royal Purple that might adversely effect the way your synchros work. I use MT-90 in my Toyota manual transmission and it works great. I wouldn't mix it with the MTL.


That's good to know- I wasn't aware that the RP was a 'masquerade' GL5. I thought that it was a pure GL-4. What's funny was that I was reading the label in Pep Boys last night and it made no reference to any specifications whatsoever, and even the description was kind of vague as to whether it was good for brass synchros- despite the name of the fluid!

Quote:
I would probably go with Redline MT90.

Instead of mixing MTL and MT90 to make some kind of hybrid, they now sell MT85 that fits nicely between the two.


Thanks- I wasn't aware of the MT85.


Quote:
http://www.amref.com/Media/Files/bp_pb/7729_BP_PG1_Classic_MP_GL4_Gear_Oil_PB.pdf

Glockner Oil Company in Columbus, OH distributes Brad Penn.


I actually didn't realize that Brad Penn made a GL4, as the only place I've ever seen Brad Penn oils are at JEGS, and they seem to always be poorly stocked on the shelf in comparison to Redline and RP. For the price, it's quite a bargain compared to RL and RP.


Quote:
See my suggestion

https://bobistheoilguy.com/forums/ubbthr...mod#Post4414328

and mightymousetech's suggestion in previous post.


Molakule, forgive my ignorance, I was under the impression that the GM/Delco Synchromesh was the same as the Pennzoil Synchromesh? Also, per BigD1's post:

Quote:
Brad Penn is stating the opposite regarding friction modifiers on synchronized transmissions saying it can interfere with proper synchronizer performance. Please explain!


The general consensus I've gathered from teh interwebz is that brass synchros need little-to-no friction modifiers because it becomes 'too' slippery- hence why GL-5s are not recommended for transmissions like that.
 
I wanted to give an update on my situation.

My first choice was the Motorcraft fluid. Apparently this is a pretty popular Gear Oil because all the dealers I contacted were out of it. The one that did have it in stock had one quart- and wanted 23.00 for it. I had to pass.

My second choice was the Brad Penn. Jegs and Summit are both out, and after calling the company it turns out Glockner has it on backorder until July. Something about the base stock they use temporarily being unavailable, due to something about Qatar being sanctioned and their supplier running out. I asked if this was SOPUS and they couldn't confirm or deny.

I was tempted to try the JEGS brand 75w90 but the label was so vague it made no mention as to whether it was a GL-4 or GL-5. Does anyone know who manufactures it?

The only option was Redline, so I went with the MT90. I figured if it was too thick, I would change it out by winter. But holy smokes! I changed it out today and have about 20 miles on it, but my shifting is coming back. Fourth gear is still kind of iffy as I get a lot of resistance going from 3 to 4, but it's already starting to feel normal again.

If anyone reading this has a Mazda or Ford manual transmission spec'd for GL-4 gear oil or ATF, I highly recommend upgrading to Redline MT90. I hope that after a few hundred miles it gets even better, but so far it seems to be correcting the problem that Pennzoil Synchromesh created.
 
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