mr brg educate me! Gear Oil

[POS Racing]

From an another post:

It sounds like a trans issue to me. Now you can tell me about how you're running a GL-5 gear oil. Then, 90% of the forum will say that Lord BRG Aryamehr The Imperial, Esq. is wrong and that GL-5 can be used in a GL-4 specified "yellow metal" trans. A few years ago I'd go through the motions and provide a study on yellow metal synchronizers and how the EP modifiers in the GL-5 hold a bond stronger than the material strength of the synchronizer causing the grind. Then, if by some chance you are a member of the 10% who choose to wing it, heed my advice fueled by the Illuminati of the lubricant world, you will try AMSoil MTG and be rewarded with a synchronizer that will eventually fix itself as my old 5-speed did.

I'm not liking my 1st to 2nd shift the transmission in my '94 feels like it is dragging as it heads to 2nd. Seems as if it is getting worse. I have Mobil One Gear Oil in it now.

I cut and pasted the above from another post but I'm thinking mr brg is wise.

Any other sources for GL4 gear oil? Or is Amsol the best choice?

Seems as if many tout they are both GL4 & GL5 compatible.

[trickyrix]

When I first got my car, the 1-2 shift action was trash, especially when ice-cold. I swapped to the Motorcraft full-synthetic gear lube and that improved things immensely. Now, three years down the road, that synchro is starting to get a little balky again. On recommendation by Wags (and Trey) I'm switching to Amsoil next time I replace the lube. In fact, it's already sitting on a shelf in my garage.

[SirHustlerEsq]

I recommend you run Penzoil synchromesh for a while since it's cheap and GL-4, available at Vatozone, to clean out all the old GL-5 until shifting cleans up; you can also pour in a quart of cheap ATF to accelerate the cleaning.

Then your options are slim...Redline MT-90 or AMSoil MTG which holds viscosity at temp a touch better at higher temps; leave the Synchromesh in if you don't track it (like my daily). If you track the car AMSoil is a must in my opinion because your sustained gear oil temps are 275*f on the track, my temp strip hit 360*f (same temp as my calipers). If you buy the MTG do yourself a favor and get the $10 pump that AMSoils sells, it makes life much easier.

I currently have some creative heat shielding around the exhaust and we'll see after a track day if that reduced temps at all. I'm currently toying with the idea of a Mocal pump trans cooler set-up to help with extending the life of the trans but only on the notion that a 100*f drop in trans temp will lead to extended life of the gears inside which I have not had a problem with on my 6-speed.

[POS Racing]

Thanks mr brg I'm going to get some Penzoil syncromesh in it to clean it out before I switch to the Amsoil.

[Radio-Active]

The Amsoil distribution center is open M-F 9-5 and located in Arlington south of Six Flags. Get your Prefered Customer card. It will pay for itself the first time you order.

[Titus]

So Trey, what about oil for the diff?

[sammm]

I understand the problem, but don't understand the reasoning. Several of us have been using Mobil-1 synthetic gear oil for years now (in the tranny and in the diff's). I've run it in all 4 of the Miata's I've owned. No one has ever had a lubrication issue before that I remember.

PS
I'm not a track guy, but autocross regularly.

[POS Racing]

I understand the problem, but don't understand the reasoning.

The bad 1st to 2nd gear shift is what made me look into this deeper and I had remembered mr brg doing some pretty extensive research on the subject. Figure this is cheaper and more logical first step to take then to replace /rebuild the transmission. Since the 1-2 shift now annoys me.

From my limited understanding there is more crap in GL5 fluid which hangs onto the syncos.

Car is in the air now draining out all the Mobil One hopefully after some miles I'll be able to report back if anything changes.

[Mark52]

Sounds like the Amsol or Redline might be overkill for us auto crossers. I, too, have been using Mobil1 for many years, but I will give the GL4 stuff a try this coming season. Who knows, it might even solve my second to fifth shifting problem (wishful thinking)...


I wonder if fifth gear lockout plates are legal in the Prepared class? Worth looking into.

[POS Racing]

Oh yea and I did read this on the interweb! (Miata.net garage)

If notchy or difficult shifting is experienced, some Miata.netters have recommended the use of synthetic transmission oils, such as Amsoil and Redline MTL. Some users of Redline MTL ($7-8/quart) have experienced smoother shifting, particularly the 1-2 shift when the engine is cold. The effect appears to be more pronounced in colder climates. MTL is a 75w-80 GL-4 gear oil that apparently behaves like a 75w-85 oil when warm, according to the company. Recent net.discussions have indicated that some Amsoil users have reported similar benefits. Proponents have also comments that use of MTL provides a "buttery feel" when shifting, and compensates somewhat for aftermarket shift knobs that are shorter (and thus require additional shifting effort). However, not all users of either Amsoil or Redline have reported benefits. As a result, it appears that either, both, or none of these lubricants may or may not be helpful for improving cold weather shifting, depending on transmission use, and/or local weather conditions.

[sammm]

Interesting...looking forward to your findings.

[SirHustlerEsq]

So Trey, what about oil for the diff?

Any GL-5. I put M1 in mine last year, but now it has AMSoil 75w90 severe gear. It doesn't really matter.

[POS Racing]

Well drove the poor thing to work this morning and it was cold!

It seemed to shift better especially 1st to 2nd but then again it could just be wishful thinking at this point.

[POS Racing]

OK I've put a little over 300 Miles on the car and the Penzoil Syncromesh has made a huge difference!

Shifts are much smoother especially 1st to 2nd. For my car it is a night and day difference! YMMV

I plan to run about a 1,000 miles on the synchomesh then change it out again with another round of syncromesh durring the off season to clean out the transmision best I can. Then maybe when AX season kicks in I may "upgrade" to the Amsoil!

Read all you want on the interweb about the GL4 vs. GL5 pissing matches but I can tell you it is a lot easier just to listen to mr brg!

[jrj512]

OK I've put a little over 300 Miles on the car and the Penzoil Syncromesh has made a huge difference!

Hmmm, tempting.

[SirHustlerEsq]

If it fixes itself, don't change it; run it for years. I think you only "need" the synthetic MTG if you're going to put heat through the trans, which you won't on the auto-x. However the Synchromes is definitely on the thin side after 30-minutes of driving. People always looked at me like an idiot when I said I have no preference from the 5 to 6-speed...ok well maybe that's an overstatement but my 6-speed shifter feels damn good on gear selection and engagement, almost as good as the 5-speed. It's nice to see the trans fix itself with a gear oil change.

[Jiggerachi]

I too have ran Mobile One gear oil for the last 5 years and have what feels like a couple dying syncros. Specifically any shifts into 3rd (upshifts and downshifts) are sometimes scratchy, more pronounced on hot summers. 2nd gear has started making a groaning noise when downshifting.

This weekend I went with the Syncromesh advise and threw in 1.something qts of syncomesh and a little less than a qt of cheap ATF. I'll run that for a few weeks, since it's a daily driver and drain it when I finally get around to the clutch job.

Will report back what happens.

[johnwag]

I'm an AMSoil dealer, btw.

[Hard Drivin Johnny]

Is the Pennzoil Synchromesh fluid the same as the General Motors Synchromesh fluid? I used to have a little Geo Storm hatchback that called for that fluid, and a mechanic friend said it was really good stuff, that other manufacturers (Mitsubishi, maybe?) had called for using it instead of what they originally spec-ed from the factory. It was a 91 model car that I had, back in 2004 and 2005, about 110k on it, and it shifted beautifully. I think I paid $10 for a quart of it at the Chevy dealer.

[Jiggerachi]

FWIW after a few month's of the pennzoil syncromesh and the new clutch, I've had noticeably less trouble with the 3rd gear scratch. It's still there occasionally, but it's low enough to possibly be driver error.

Could have also been the clutch or the motor mounts, the clutch was mechanically shot to hell, all the springs were broken and partly missing. The motor mounts both fell out in pieces as well.