# Synthetic manual transmission gear oil **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** forte, kia\ **Created:** [May 29, 2017, 12:10am UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431 "2017-05-29T00:10:14Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![sgtrock21](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/sgtrock21/32/246_2.png) [@sgtrock21](https://community.cartalk.com/u/sgtrock21)\ **Post date:** [May 29, 2017, 12:10am UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431/1 "2017-05-29T00:10:14Z")
2010 Kia Forte SX 6spd M/T. Does MT-85 75W85 GL-4 Gear Oil - Red Line Synthetic Oil have the distinctive “onion” smell of decades old 90W? I have an oil leak (spots on driveway) since Wednesday but engine oil is 100% full. Car was serviced with oil and filter change at Kia dealer 30 days ago. I placed a plastic tray under the car and leak seems to be about one ounce per day. Transmission capacity is 1.9 quarts. Oil leaking looks, feels, and smells like engine oil but I have no idea what current M/T gear oil looks, feels, or smells like. Of course medical and vehicle problems always seem to happen on holiday weekends. I have an appointment at the Kia dealer Tuesday morning and am reasonably sure the 16 mile trip should be uneventful. ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [May 29, 2017, 2:10am UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431/2 "2017-05-29T02:10:51Z")
A sudden oil leak 30 days after service, I would not assume it has to be the transmission. It is more likely engine oil and probably due to an error in servicing. Worse case, the oil plug was not properly tightened and it falls out on the way to the dealer. More likely, the oil filter was over tightened and the gasket got a little tear in it and is now leaking. A few drops a day will not drop the oil level a measurable amount in just 30 days. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [May 29, 2017, 1:37pm UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431/3 "2017-05-29T13:37:17Z")
Synthetic gear oil smells like motor oil. It is thicker, sure, but doesn’t have the strong smell of the old days. It can smell if its been hot but not like the past. I’d be surprised if the Forte uses gear oil for the trans. Most manuals these days use something much lighter in weight, like ATF if not actual ATF. ---
**Author:** ![wentwest](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wentwest/32/6073_2.png) [@wentwest](https://community.cartalk.com/u/wentwest)\ **Post date:** [May 29, 2017, 4:29pm UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431/4 "2017-05-29T16:29:58Z")
I found very little info in a Google search, but I did find the thread below in a Kia forum. > **[How to check/fill forte koup manual tranny fluid? - Kia Forte Forum : Sedan /...](http://www.forteforums.com/forums/koup-general-discussion/6996-how-check-fill-forte-koup-manual-tranny-fluid.html)** > > Kia Forte Forum : Sedan / Koup / Forte5 Forums And, you can contact Red-Line directly and ask them what color the fluid is. Red Line Synthetic Oil 6100 Egret Court Benicia, CA 94510 PHONE: (707) 745-6100 or (800) 624-7958 FAX: (707) 745-3214 ---
**Author:** ![sgtrock21](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/sgtrock21/32/246_2.png) [@sgtrock21](https://community.cartalk.com/u/sgtrock21)\ **Post date:** [May 29, 2017, 6:41pm UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431/5 "2017-05-29T18:41:18Z")
Gear oil spec is from the owner’s manual. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [May 30, 2017, 12:12am UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431/6 "2017-05-30T00:12:49Z")
Even though the owner’s manual says “gear oil” Red Line MT-85 is not technically gear oil. It’s manual transmission oil (thus the MT in its name). Its friction additives are set up for synchronizers. It doesn’t have the strong sulfur smell of gear oil and has an odd pink color when new. ---
**Author:** ![sgtrock21](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/sgtrock21/32/246_2.png) [@sgtrock21](https://community.cartalk.com/u/sgtrock21)\ **Post date:** [June 1, 2017, 6:56pm UTC](https://community.cartalk.com/t/synthetic-manual-transmission-gear-oil/104431/7 "2017-06-01T18:56:40Z")
It was a worn oil drain plug. Plug and oil replaced no charge. No more leeky.