Gear oil/tranny

[j-gt4specs]

ok what is recommended for the oil on the tranny what grade and so forth??? i use mobil 1 for motor but the tranny?

[3sgte@daspeedof]

crappy tire carries gear oil 75w90, redline is the best or royal purple.

[No Spin]

Doubt there is a Canadian Tire in Sad Diego, but I have been wrong before.

This question opens a can of worms, I have done some searching on it and it has been covered a few times. You will get replies of ATF, Penzoil Synchromesh, Motul, Redline, etc.

Our specs say you need a GL5 - which is a spec for a lot of extreme pressure additives. These same additives that are recommended are known to cause a lot of wear on certain synchros. Our synchros appear to be the weak link from what I have been reading. The Synchromesh users(not GL5 rated) claim much improved shifting. Others fear that non GL5 oil may damage the synchros.

Confused yet?

I am, since the manufacturer recommended product may to be the one that causes the synchro troubles that many have. This quote was from the Pennzoil site.

API GL-4 and API GL-5 products typically use the same extreme pressure (EP) additive system, with the API GL-5 having about twice the concentration of a API GL-4. In service, these additives become active under extreme load and temperature when the protective oil film can be squeezed away. EP additives work by forming wear-resistant compounds with the metal of the gear tooth surface. As the gears mesh, these compounds shield the gear teeth from direct metal-to-metal contact that would cause wear and damage to the gears. If too little of the active additive is present, proper protection would be compromised. Too much of this additive could cause excessive chemical corrosion of the gear surface. If an API GL-5 gear oil is used in a application where API GL-4 gear oil is called for, chemical corrosion of "yellow metal" components may occur, such as bronze synchronizers, brass bushings, etc. This may lead to shifting difficulties or shortened equipment life.

I haven't had the pleasure of ripping apart my tranny yet, but can anyone confirm if we have "yellow metal" components like the bronze synchros, etc?

I would say without further info that the better choice may be the Redline but if your synchros are hurting you may have little to lose by giving the Pennzoil a try. My 2 1/2 cents.

[omgitsroy326]

synchromesh by penzoil

[Rick89GTS]

This is always one of those much-debated questions about our cars.
Someone here must have torn down one of our trannys before. I'd be interested in the "yellow metals" thing too....

[j-gt4specs]

Yea I would like to know of that [qoute]API GL-5 gear oil is used in a application where API GL-4 gear oil is called for, chemical corrosion of "yellow metal" components may occur, such as bronze synchronizers, brass bushings, etc. This may lead to shifting difficulties or shortened equipment life. [/qoute] Reason I plan to change it because I grind on 2nd even on normal driving I knw its a normal thing but just seeing if maybe changing gear oil may help. **note 2nd grinds sometimes.

[No Spin]

Just so it is perfectly clear: the quote refers to using GL5 in GL4 specified uses. Toyota recommends the use of GL5 so the quote above is not referring to our specific use.

The information does, however, raise the question of why so many of our trannies seem to have this synchro issue. Did the GL5 spec hasten the problem with the synchros?

That is why I was interested in knowing about the "yellow metal", ie: do we have bronze synchros?

[No Spin]

Last Saturday I did the tranny oil change to Synchromesh. I previously had to be precise with the 2nd gear shifts, both up & down.

Much smoother shifting this week. I give it a thumbs up so far. I'll check it again after the winter is over.

[Stubble]

http://www.alltrac.net/phpBB2/viewtopic ... tranny+oil

The GL-5 rating is required (says toyota) to protect the hypoid gears in our tranny and transfer output. I had my tranny rebuilt to replace the synchros, but it didn't help much. I am using GL-5 right now.

I had 200,000km on my tranny, and the hypoid in the transfer case was pristine. So, the GL-5 does its job. For improved shifting, it might be worth sacrificing some hypoid life (ie use Synchromesh instead of GL-5). It's a Toyota gearbox - it's going to last a long time regardless. If you only plan on keeping the car for a few years, what the hell. The next owner will not notice excessive wear on the hypoid gears, but chunky shifting will turn him off.

[img]http://img377.imageshack.us/img377/7656/transferoutput55qm.jpg
Hypoid gear = spiral bevel


And the replacement synchros looked bronze to me, but there could have been a yellowish plating on them as well. I didn't pull out my scanning electron microscope to confirm.

[No Spin]

Nice visual. I am in agreement with you on the synchro vs gear wear issue. Since the labor is the killer in going into the tranny what good is having great gears when
you can't shift?

The Synchromesh is well worth the swap from GL5 so far.

[Stubble]

The Synchromesh is well worth the swap from GL5 so far.

Did you mix it or use it full strength?

[No Spin]

I put 100% Synchromesh in.

[___Scott___]

Just as an FYI, I've read in other threads where people claim Synchromesh is not compatible with yellow metals. Pennzoil thinks otherwise, a snip from their site:

It provides excellent oxidation stability, low temperature performance, excellent synchronizer performance and compatibility with yellow metals, such as bronze, brass and copper components found in manual transaxles and transmissions.

My personal experience is that Mobil1 synthetic gear lube renders the synchros useless. ATF was a big improvement over the synthetic, but still not what I wanted. Synchromesh has been working very well ever since, but it seems I didn't keep a record of when I switched and I don't remember how long it's been in there.