Opinions on synthetic manual tranny/diff fluid vs gear oil?
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Opinions on synthetic manual tranny/diff fluid vs gear oil?
I've done some searching, and really couldn't find anything specific about manual transmission fluid. I've been advised to fill my new JDM tranny with Redline MTL fully synthetic fluid instead of the 80W90 gear oil I was using on my OE 'mission. This stuff is expensive, and it sounds nice, and I know I need 3.5 quarts of it... Do we have an LCO consensus on the benefits of synthetic fluid vs gear oil for our transmissions? What do you guys think, any experiences that might be helpful?
Would I be wasting my money on this stuff or would it be a good idea...? (and of course, why)
Would I be wasting my money on this stuff or would it be a good idea...? (and of course, why)
Last edited by free5ty1e on Tue Aug 22, 2006 6:49 pm, edited 2 times in total.
-Chris
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
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- Fifth Gear
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Also... should I put the same stuff in my new rear 4.11 LSD? The front differential shares fluid with the 5MT correct? So how much of this stuff do I actually need?
-Chris
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
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- Fifth Gear
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- Joined: Wed Nov 12, 2003 12:26 am
- Location: USA: Portland, OR (Tigard, ~200ft elevation)
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Wait... I'm reading up on these GL ratings, and Redline MTL is a GL-4 oil. Do our transmissions require GL-5 oil? I'm confused.
My front and rear differentials are specified as "hypoid" in the 1992 FSM, so does that mean they need GL-5? And since the front differential shares fluid with the tranny, that means the tranny and differentials all need GL-5, and the same stuff?
From http://www.racerpartswholesale.com/redtech4.htm :
"Most manufacturers of manual transmissions and transaxles recommend an 80W or 90W GL - 4 lubricant. GL - 5 gears oils which are required in hypoid differentials are not used in most synchromesh transmissions because the chemicals used to provide the extreme pressure protection can be corrosive to synchronizers, which are commonly made of brass or bronze. Typically, the use of a GL - 5 lubricant in a synchromesh transmission will shorten the synchronizer life by one half. The extreme pressure requirements of spur gears and helical gears found in transmissions are not nearly as great as found in rear-wheel drive differentials. A GL - 4 lubricant provides adequate protection for most manual transmissions, unless a unique design consideration requires the extra protection of a GL - 5."
My front and rear differentials are specified as "hypoid" in the 1992 FSM, so does that mean they need GL-5? And since the front differential shares fluid with the tranny, that means the tranny and differentials all need GL-5, and the same stuff?
From http://www.racerpartswholesale.com/redtech4.htm :
"Most manufacturers of manual transmissions and transaxles recommend an 80W or 90W GL - 4 lubricant. GL - 5 gears oils which are required in hypoid differentials are not used in most synchromesh transmissions because the chemicals used to provide the extreme pressure protection can be corrosive to synchronizers, which are commonly made of brass or bronze. Typically, the use of a GL - 5 lubricant in a synchromesh transmission will shorten the synchronizer life by one half. The extreme pressure requirements of spur gears and helical gears found in transmissions are not nearly as great as found in rear-wheel drive differentials. A GL - 4 lubricant provides adequate protection for most manual transmissions, unless a unique design consideration requires the extra protection of a GL - 5."
-Chris
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
Uh,...Scotty's cocktail...check out my writeup and recipy in the reviews section...
93SS 5MT White, TD05-16G, TMIC, 3"Turboback, Magnaflow, Alu Rad, H&R Sports, AGX struts, F/R STBs, Whiteline Sways, ALK+Endlinks, Odyssey 925, AC delete, Evo8 Recaros, Sparco 4p, 3.9 LSD, Hellas+air horns, IPD short throw, 99RSrims, s03's
Re: Opinions on synthetic manual tranny/diff fluid vs gear o
Back from the dead thread. I just put Valvoline non syn 75w-90 in the rear diff for a scheduled 30k interval change. Our car is a 94 L awd 5 spd (135k). What can I safely and economically put in the front for tranny/diff fluid?
Re: Opinions on synthetic manual tranny/diff fluid vs gear o
Generally any GL-5 gear oil of the proper weight will be fine. Some work better with the synchronizers than others though. Subaru's Certified Gear Oil is a good choice if you want to spend lots of money. From my readings it seems Subaru stuff and Amsoil Severe Gear seem to be the favorites. Valvoline and Mobil make decent regular priced gear oil.
I wouldn't recommend going with Uncle Scotty's Cocktail in a regular DD as it causes accelerated synchro wear and needs frequent changing.
I wouldn't recommend going with Uncle Scotty's Cocktail in a regular DD as it causes accelerated synchro wear and needs frequent changing.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!
05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
Re: Opinions on synthetic manual tranny/diff fluid vs gear o
proper weight? 80-90? 75-90?
Re: Opinions on synthetic manual tranny/diff fluid vs gear o
IIRC synthetics its 75-90, mineral oil is 80-90.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!
05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
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Re: Opinions on synthetic manual tranny/diff fluid vs gear o
Either range should work fine.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote: ↑Mon Jan 14, 2002 10:23 am Wait....I'm confused now.
Re: Opinions on synthetic manual tranny/diff fluid vs gear o
75-90 is the factory recommend weight, but 80-90 will work as Mike pointed out.
Josh
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
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- Fifth Gear
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Re: Opinions on synthetic manual tranny/diff fluid vs gear o
I've found Subaru Extra-S to be better than Redline 75w90 (NS or regular), when cold or hot. Redline didn't seem to work as nicely with the synchros. Regular Valvoline was way worse than that. This is in a transmission from a BD with lots of miles on it.
90 L+ wgn