AMSOIL guide
AMSOIL Manual Transmission Fluid Guide
AMSOIL builds three different products that go in a manual gearbox depending on what your owner's manual calls for: Synchromesh Transmission Fluid (5W-30) for GM, Chrysler, Honda, Mopar synchromesh specs, Synthetic Manual Transmission & Transaxle Gear Oil 75W-90 (GL-4) for European 75W-90 GL-4 transaxles, and Multi-Vehicle ATF for the manual gearboxes that specifically call for ATF. Pick by what the manual specifies, then use the GL-4 vs GL-5 rule to verify: GL-4 for synchros, GL-5 for hypoid diffs.
AMSOIL manual transmission fluid lineup at a glance
| Fluid | Best fit | Where to buy |
|---|---|---|
| Synchromesh MTF (5W-30) | GM Synchromesh, Chrysler MS-9224, Honda MTF, Mopar MTL | Buy online | Product details |
| Synthetic MTG 75W-90 (GL-4) | European 75W-90 GL-4 transaxles (VW, BMW, Mini, Volvo) | Buy online |
| Multi-Vehicle ATF | Tremec, Toyota R-series, and other ATF-spec manual gearboxes | Buy online | Product details |
The GL-4 vs GL-5 rule
Manual transmission fluid is governed by the API gear-oil service categories. GL-4 uses a moderated sulfur-phosphorus extreme-pressure additive package that protects gears without corroding the brass and bronze synchros found in most manual transmissions. GL-5 uses a higher-EP additive package designed for the heavy gear shock found in hypoid differentials and final drives.
The rule is simple: GL-4 in the manual transmission, GL-5 in the differential. Putting GL-5 in a manual gearbox that calls for GL-4 corrodes the synchros and ruins shift feel within a few thousand miles. The matching 75W-90 gear oil guide covers the GL-5 side for differentials and transfer cases.
Synchromesh: GM, Chrysler, Honda, Mopar
AMSOIL 5W-30 Manual Synchromesh Transmission Fluid is the standard pick for GM Synchromesh (12345349, 12378508, 88861800), Chrysler MS-9224, Honda MTF, and Mopar Manual Transmission Lubricant. The 5W-30 viscosity targets smooth synchromesh shifting with minimum gear wear in modern manual gearboxes from GM, Chrysler, Honda, and Mazda.
European 75W-90 GL-4 transaxles
European front-wheel-drive manual transaxles (many VW, BMW, Mini, and Volvo applications) specifically call for a 75W-90 GL-4 fluid. AMSOIL Synthetic Manual Transmission & Transaxle Gear Oil 75W-90 covers those applications. Do not substitute a 75W-90 GL-5 hypoid gear oil; the higher-EP additive package corrodes the synchros. See the AMSOIL 75W-90 gear oil guide for the full GL-4 vs GL-5 breakdown.
Manual gearboxes that call for ATF
Some manual transmissions, particularly older Tremec (Ford Mustang T-5, T-56) and Toyota R-series gearboxes, specifically call for ATF instead of a synchromesh-spec MTF or a GL-4 gear oil. Use AMSOIL Signature Series Multi-Vehicle ATF in those applications. The AMSOIL ATF guide covers the full multi-vehicle approval list.
Bottom line: which AMSOIL manual transmission fluid should you pick?
- GM, Chrysler, Honda, or Mopar synchromesh-spec gearbox. Pick AMSOIL 5W-30 Synchromesh MTF (also online from AMSOIL).
- European 75W-90 GL-4 transaxle (VW, BMW, Mini, Volvo). Pick AMSOIL Synthetic MTG 75W-90.
- Tremec, Toyota R-series, or other ATF-spec manual gearbox. Pick AMSOIL Multi-Vehicle ATF.
- Hypoid differential. Use a GL-5 gear oil; see the 75W-90 gear oil guide or 80W-90 gear oil guide.
Save on AMSOIL with Preferred Customer pricing
AMSOIL Preferred Customer membership is $20 USD per year ($10 USD for a six-month trial) and unlocks up to 25% off on every product, with free shipping on qualifying orders. Add the membership to the same cart as your order and qualifying products switch to member pricing on that checkout, with no separate sign-up step. See the breakdown on the AMSOIL Preferred Customer page, or sign up directly through the AMSOIL Preferred Customer enrollment page.
AMSOIL manual transmission fluid FAQ
What is the difference between GL-4 and GL-5?
GL-4 and GL-5 are API gear-oil categories. GL-4 is the right pick for most manual transmissions because the active sulfur-phosphorus EP additive level is moderated to protect the brass and bronze synchros. GL-5 is the high-EP category for hypoid differentials. Putting GL-5 in a manual transmission that calls for GL-4 corrodes the synchros and ruins shift feel.
What does AMSOIL Synchromesh Transmission Fluid replace?
AMSOIL 5W-30 Manual Synchromesh Transmission Fluid is a 5W-30 GL-4 fluid designed to replace GM Synchromesh (part 12345349, 12378508, 88861800), Chrysler MS-9224, Honda MTF, Mopar Manual Transmission Lubricant, and similar synchromesh-specific specs. Same product is available online from AMSOIL.
My manual gearbox calls for ATF. Can I use AMSOIL ATF?
Yes. Some manual transmissions (particularly older Tremec, Toyota R-series, and others) specifically call for ATF rather than gear oil. Use AMSOIL Signature Series Multi-Vehicle ATF in those applications. Verify against the OEM-specific spec on the fluid-fill plug or the owner's manual.
What about a 75W-90 GL-4 manual transaxle?
For European front-wheel-drive manual transaxles (many VW, BMW, Mini, and Volvo applications) that specifically call for 75W-90 GL-4, use AMSOIL Synthetic Manual Transmission & Transaxle Gear Oil 75W-90 (MTG). Do not substitute a 75W-90 GL-5 hypoid gear oil. See the AMSOIL 75W-90 gear oil guide for the GL-4 vs GL-5 breakdown.
How often should I change manual transmission fluid?
Most owners' manuals call for a change every 50,000 to 100,000 miles. Severe service (track use, towing, mountain driving) pulls the interval to the shorter end. Manual gearboxes that get short fluid changes show measurably less synchro wear over 100,000+ miles than gearboxes run on the original fill.
Where do I buy AMSOIL manual transmission fluid?
Order online from AMSOIL on the manual transmission fluid page. The matching transmission fluid overview covers the full lineup of MTF, ATF, CVT, DCT, and PowerShift fluids in one place.
Order AMSOIL MTF
Order online from AMSOIL's manual transmission fluid page. To unlock up to 25% off, add an AMSOIL Preferred Customer membership to the same cart and qualifying products switch to member pricing immediately, with no separate sign-up step.