Help me regarding my new synthetic gear oil

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White95Max

New member
I just got my package of RedLine synthetic gear oil. It says it's 75W-90 and GL-5, which matches the requirement in the owner's manual. However, it says on the back of the bottle...



"This product is not designed for use in most manual transmissions, since the extreme slipperiness may cause gear clash."



What's the deal? Should I send it back?





Here's what else it says on the bottle:



SAE 75W90 API GL-5 Hypoid Gear Oil

Highest performance in limited-slip and conventional differentials

Provides greatest gear protection available

Reduces differential and gearbox temperatures

Improves drivetrain efficiency up to 2-5%

Contains additive for limited-slip differentials

Recommended for API GL-5, GL-6, MT-1, MIL-L-2105E, and SAE J2360

Compatible with petroleums and synthetics

Suitable for racing and street use

Excellent for high- & low-mileage differentials
 
well it should work and i think it would be fine but after trying to figure out what i should put in mine it made my head spin....



I went with amsol..



here is a tech artical about gear oil from cobb tuning





Gear Oil Technical Info









One common complaint about Subaru manual transmissions are how notchy they feel. A common step taken to help reduce this notchy feeling is to use a better gear oil. But which one do we use? Which one works best? Good questions, unfortunately there's no right answer for everyone.



Internal Conflict - Bearings vs Synchros

Inside your manual transmission, you have two key components that actually require different things to work optimally. Finding the right gear oil for you will depend on what transmission characterists are most important to you. Please read the following explaination to help you decide.





Bearings

The bearings want lubrication. The more they can get, the happier they'll be and the longer they'll live. Your bearings are at work when your car is in gear and you're driving around. Making the bearings happy gives you a quieter, cooler running transmission with lower power comsumption and better gas mileage.



Synchronizers

The synchros, on the other hand, want some friction. Synchronizers are used to bring the gear you're shift to (ie: 4th into 5th) up to speed so that the gears match up without any grinding. In order to do this, they rely on friction. If they get the friction they need, they can perform their job very quickly, allowing quick, smooth shifts. If they don't get the friction though, they can be very tempermental.



Synthetic or Not?

In our opinion, synthetic oil is a great choice. By design, synthetic oils can handle the heat much better than conventianal oils giving you better protection. Most people associate Synthetic with having a high lubrication property, but there are some synthetics designed high less lubrication which favors the synchronizer. We'll take a look at those shortly.





Which gear oil is best?

Going back to our INTERNAL CONFLICT, we must decide on how we drive our car and what we want to achieve. If you typically drive long distances and/or do very little agressive shifting, you're probably best going with a high lubrication, bearing friendly gear oil. However, if you tend to drive and shift more frequently and agressively, then you might want to consider choosing an oil with less lubrication. Yes, the extra friction might reduce bearing life but if you're potentially going to hurt a synchro and/or gear otherwise, bearing life is a moot point.





Below are a list of a few popular gear oils. Our recommendations are just that, recommendations. We're not making any guarantees or official endorsements of any particular product. We're just trying to help you make up your mind as to what will work best for you.



NOTE: All Subaru AWD Transmissions use a 75W90 Oil. The rear end, including the 2000 models w/ viscous rear diff, also uses a 75W90 oil without friction additives.



REDLINE OIL

MTL This oil is too low of a viscosity to be used in the Subaru AWD manual transmission. Not Recommended.

MT-90 Great balance of friction and lubrication. This is a good choice for a street/auto-x car. Highly Recommended.

75W90 A GL-5+ grade oil which has a friction modifier and is more suited for a mechanical limited rear end instead of the transmission. If you want friction in the transmission, use the MT-90.

75W90NS Another GL-5+ oil which offers good lubrication and bearing life. Best for the rear diff but can be used in the transmission.

Shockproof Expensive but a good oil for those who are abuse to the transmission/rear end and/or do quite a bit of racing. Use the SuperLight rated oil. Not a requirement for everyone but good stuff nonetheless.





AMSOIL

Series 2000 75W90 Affectionately called "Smurf Oil" due to it's blue color. Great lubrication properties make it the gas mileage king. Take alot of long trips? Smurf oil is the ticket. Used and developed for fleet vehicles, not recommended for quick shifting drivers.

75W90 Great lubrication properties. Less expensive than the Series 2000 but still works very well. Very good bearing life. For those that favor bearings over synchros, Amsoil is one of the best!





More reviews coming soon...



Conclusion

As you can see, there isn't necessary a BEST OIL that can be recommended to everyone. It really depends on how you drive the car and your particular needs. Some owners find that they try 2 or 3 different oils before they find the one that suits them best. Don't be afraid to experiment and if you want to share your experiences with us, please send them in and we'll try to share your results with others.
 
holland_patrick said:
75W90 A GL-5+ grade oil which has a friction modifier and is more suited for a mechanical limited rear end instead of the transmission.



AMSOIL

75W90 Great lubrication properties. Less expensive than the Series 2000 but still works very well. Very good bearing life. For those that favor bearings over synchros, Amsoil is one of the best!
Click to expand...





Yeah once again it says that the RedLine 75W-90 is suited for limited-slip rear ends, not transmissions.



Maybe I'll send it back and get some of that Amsoil 75-90 stuff. Where did you get yours Patrick?
 
They have the 75W90 NS, which doesn't have the limited slip modifiers in it.



They also have MT-90, for manual transmissions, which they claim is best for Hondas, Mazdas and Toyotas. However, it's GL-4, so I don't know if it will work for your Protege.
 
Something else to take a look at is Amsoil's NEW synthetic manual transmission fluid. I am not sure if it meets the specs of your transmission but, it is worth a look see.



http://www.amsoil.com/StoreFront/mtf.aspx



mtf_qt_350pxh.jpg




Here is a link to their 75W90 synthetic manual transmission and gear lube that others have mentioned in this thread.



http://www.amsoil.com/StoreFront/mtg.aspx



mtg_qt_350pxh.jpg
 
I got it local and had All my fluids changed at the same time for 132. ya i know it might be a lot for something i could do my self but then i have to sidpose of oil and stuff so. i did it this way.





cobbtuning.com sells both i think that is where i got the artical from
 
My wife used to have a little 4WD Daihatsu (known over here in UK as a Sportrak) and it had real problems with changing gear (crunch just was'nt in it!). However, the manufacturer recommended that for the first 50,000 miles that she use Automatic Transmission Fluid rather than gear oil in the gearbox. This certainly did the trick - no crunching gear changes!. Once she reached the 50,000 miles the garage changed back to normal gearbox oil (can't remember the type though). The gears were a still little stiff but the crunch had gone!

Reading the previous comments suggests that perhaps a different gearbox oil could have sorted the problem at the time?
 
arc said:
They have the 75W90 NS, which doesn't have the limited slip modifiers in it.



They also have MT-90, for manual transmissions, which they claim is best for Hondas, Mazdas and Toyotas. However, it's GL-4, so I don't know if it will work for your Protege.
Click to expand...



The owner's manual states that any GL-4 or GL-5 75W-90 oil will work. I forgot about the MT-90. I can't return the other stuff for cash, but I can return it for an exchange, so I guess I'll just exchange this stuff for the MT-90.



I'm still not sure why I didn't notice that there were two separate buttons on the site, one for "gear oils" and one for "transmission oils". :hairpull
 
Wow, someone beat me to it.



Coming from an AMSOIL dealer this is going to shock the living daylights out of you.....



For your manual transmissions, but the SF stuff! Whenever customers ask me for manual tranny stuff I send them there. Between MTL-P/R and MTFGlide they just can't go wrong.



Their stuff is topnotch.
 
White95Max said:
I just got my package of RedLine synthetic gear oil. It says it's 75W-90 and GL-5, which matches the requirement in the owner's manual. However, it says on the back of the bottle...
Click to expand...



I think for your manual tranny you want to either use Redline MTL, or MT-90. Not the gear oils. It sounds like MT-90 is more suited to the recommendation in your manual.



So far my ZF 6-speed is liking the MTL. But then I only tried it on recommendation from other owners as well as ZF tranny experts. Maybe see what other Protege owners prefer in their cars?
 
I'm going to go with the MT-90, since I can exchange the other stuff for it at no charge other than shipping. The price per quart is the same.
 
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