GL-5 without friction modifier?

[Jim_B_in_CO]

I've got a 2007 Subaru Outback with a manual trans which calls for a GL-5 gear oil in the transmission. Am I correct in thinking an oil without a friction modifier would be best? I know Redline sells (and recommends for my car) a synthetic gear oil without the modifier. Being cheap, I'm looking to use a conventional oil. I called the Valvoline tech support line and the guy I spoke with said they add "some" friction modifier/limited slip additive to all their gear oils. Are there any good quality conventional gear oils that don't have it? I'm looking to use a 75W/90 or a 80W/90.

Thanks in advance!

-Jim

 

[Quest]

what do you mean by "friction modifier"?

Virtually all M/T gearbox oils, with the exception of limited slip (mainly for use in LSDs, but can be extended to other use sometimes) additives, most API GL-4/GL-5 comes with certain degree of friction modifiers within to provide proper friction for your synchro cones to engage.

Unless your subie comes with limited slip differentials or similar, I've never heard of M/T gear oil w/o any friction modifier or similar.

Q.

 

[Jim_B_in_CO]

Well, here's the description of the Redline 75W/90NS: Redline 75W/90NS

"This GL-5-type gear oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting."

I'm guessing (and please correct me if I'm wrong) that limited slip additive/friction modifier is added to some gear oils to allow them to function in a limited slip differential without adding an additional product like this: Limited Slip Friction Modifier.

I'm looking for something similar to the 75W/90NS, but in a conventional oil.

 

[Quest]

Ahh! You are referring to specialty products such as RedLine gear oil..
Yes, they may not come with friction modifiers because of their base oil properties.

For conventional gear oil or syn blend, certain amount of friction modifier is normally required to achieve the proper friction coefficient for your synchro to engage properly. If your Subie calls for GL-5, then use GL-5 . If you fancy full syn such as redline, amsoil, etc. go for them.

In many cases, GL-5 is a gear oil specification. It should not not be perceived as a standard for the lack of friction modifier within but more like the conformance to a certain friction coefficient for proper gear/synchro engagement. Certain blend may come with boatload of friction modifiers, while others may be able to do away without.

Q.

IMHO just shop around for the proper viscosity (75W90) and GL-5 specifications and sleep well.

 

[PT1]

Originally Posted By: Jim_B_in_CO

I'm looking for something similar to the 75W/90NS, but in a conventional oil.


Why? The Redline can't be that much more and will certainly outlast conventional.

 

[Jim_B_in_CO]

Originally Posted By: PT1
Why? The Redline can't be that much more and will certainly outlast conventional.

A) I'm cheap.
B) I think conventional gear oil works just fine (at least in "low stress" applications like my 2.5 liter non-turbo Subaru). I'm pretty sure Subaru put conventional oil in the trans at the factory and it's worked well up to this point.
C) I probably won't keep the car more than another year or two. It's got 36,500 miles on it now; the synthetic isn't likely to benefit me.

 

[Jim_B_in_CO]

Originally Posted By: Quest
IMHO just shop around for the proper viscosity (75W90) and GL-5 specifications and sleep well.

I'm starting to think you're 100% correct.

 

[FastSUV]

you can use gear oil with FM additve usually in a manual tranny...In a 75w90, it will be virtually impossible to find a gear oil without the FM because most in that weight will be formulated for limited slip diffs...I would prefer not to run it if I could get the right stuff locally, but in a 75w90, if it was me, I'd just get the best priced stuff you can find in a full-synthetic. They do make 75w90 non-syn gear oils, but I have researched and it seems that syns are best in trannies & x-fer cases, and dinos are best in differentials...Plus if you get some cheap syn, you can go longer between services..

 

[Johnny]

I just sent you a PM where to get some.

 

[Thingfish]

Why not just use Subaru extra-s oil? It is an excellent fluid, is not expensive and offers the proper protection AND syncho action for that car.

 

[unDummy]

I would use a synth. Better cold performance for those winters.

Nothing wrong with a conventional. But, most have LSD additives added. You'll have to shop around to find a gear oil without "lsd" mentioned on the bottle. Check the local truck stops/suppliers since many OTC gear oils usually don't have the additve.

Besides Redline, Motul, Ford, and Torco have GL5 gear oils with LSD additives. And, if you don't mind the dealer premium, OE is an easy option.

 

[Jim_B_in_CO]

Originally Posted By: Johnny
I just sent you a PM where to get some.

Got it - thanks, Johnny.

 

[Jim_B_in_CO]

Originally Posted By: Thingfish
Why not just use Subaru extra-s oil? It is an excellent fluid, is not expensive and offers the proper protection AND syncho action for that car.

I hadn't even thought about it - good idea. I'll give the dealer a call tomorrow and see how much they want.

Thanks for all the responses, guys - you've been really helpful.

 

[Jim_B_in_CO]

Originally Posted By: unDummy
I would use a synth. Better cold performance for those winters.

I'd agree, but what's in there now has worked surprisingly well in the cold weather. I'm guessing that's because it's a multi-grade, but I'm not sure.

 

[SubLGT]

Originally Posted By: Jim_B_in_CO
............ I'll give the dealer a call tomorrow and see how much they want.........


Cheapest I've seen is $12 per quart.

 

[gtx510]

look for GL-5's with little or no moly...

 

[Tremo]

Redline 75W90NS

Motul Gear 300

Those are the only two I am aware of, but there may be others.

 

[FastSUV]

Originally Posted By: gtx510
look for GL-5's with little or no moly...


why no moly? cause of a tranny application I assume?

I got some Mystik 80w90 and I am thinking it has plenty of moly and in a differential I was hoping that was good? Maybe just not in a tranny due to sludge?

 

[Al]

No disrespect, but when gas was $4.24 you used it. You have a 2007 vehicle, which cost a bit more than chump change, and you have cold winters where a syn will give better service and probably better fuel efficiency. I am at a loss why you chose to cheap out on a product that can give your costly vehicle better service. I mean we are probably talking less than 10 bucks difference.

No flame, just an opinion.