A How To: changing manual transmission fluid
08-11-2010, 08:08 PM
#91
Join Date: Aug 2010
Location: WA
Posts: 15
Just changed the original factory fluid in my '05 GT 5sp with 58k miles to Royal Purple (RP) Automatic Transmission Fluid (ATF). Both the Tremec 3650 manual and the Ford manual say to use ATF with a Dexron III rating in the manual trans. The RP ATF has a Dexron III-H rating. Seems like the III-H is ok in place of the straight III without the suffix. Unless you've already done it, I wouldn't put manual transmission fluid in the S197 GT manual transmission, it's designed for ATF.
By the way, the tremec manual says fill to bottom of the fill hole, not 1/2" below. I know that's different than the Ford manual but it's designed that way so it fills perfect and overflows if you put in too much. I don't think the Tremec guy was against RP; I think he was against using Synchromesh manual fluid.
Brad
By the way, the tremec manual says fill to bottom of the fill hole, not 1/2" below. I know that's different than the Ford manual but it's designed that way so it fills perfect and overflows if you put in too much. I don't think the Tremec guy was against RP; I think he was against using Synchromesh manual fluid.
Brad
I can confirm that my manual lists 'Motorcraft MERCON ATF' for the manual transmission fluid specification. Any insight greatly appreciated. I'm leaning toward following the spec at this point, unless I hear otherwise.
08-11-2010, 08:46 PM
#92
5th Gear Member
Join Date: Aug 2007
Location: Lakeland/Mulberry FL
Posts: 2,263
if you look on the RP bottle,it says it can be used in place of the mercon our trannys use......so it would seem it is compatable no problem, ive used it in 2 trannys so far and it has felt better in each one!
08-12-2010, 10:22 AM
#93
4th Gear Member
Join Date: May 2010
Location: Temple, TX
Posts: 1,277
Soooo... which is better... The Max ATF states it is Dexron/Mercon III compatible, but the description for the Syncromax states "Synchromax® is recommended for manual transmissions that specify an automatic transmission fluid or motor oil."
Why is this so danged confusing?
Don
03-15-2011, 12:04 AM
#95
i am confused about which fluid to use. i have manual 06 gt, went to o'reillys to pick up the rp syncromax, but they didnt have any in stock. i talked to an employee there and he looked up my car in the computer and told me to use the rp max atf. it says right on the bottle that its for automatics, but he said that it was fine. im a bit skeptical. does anyone know if this is okay to use? here is a pic of the bottle:
03-15-2011, 08:33 AM
#96
Join Date: Jun 2009
Location: Virginia
Posts: 12
jAAAmes, the 06 mustang GT has a Tremec 3650 manual transmission and does indeed use automatic transmission fluid (ATF). Tremec, however, recommends NOT using Royal Purple (RP). They recommend either regular ATF or Mobile 1 synthetic ATF. If you read through this entire thread, you'll find a post where someone called Tremec's tech support about this; that was the answer they received.
After reading that, I called too to ask why. They said RP has friction modifiers and they had not tested their transmissions for compatibility with them. Manual transmission synchronizers require some friction to work properly. Not wanting to experiment on my own transmission, I drained out $40 worth of RP and refilled it with Mobile I ATF.
Other people posting to this thread have said they've used RP and even synchromesh fluid with no problems.
So, bottom line, yes, the mustang maunal transmission uses automatic transmission fluid. Whether or not you want to use RP against Tremec's recommendation due to unknown compatibility, it's up to you.
Brad
After reading that, I called too to ask why. They said RP has friction modifiers and they had not tested their transmissions for compatibility with them. Manual transmission synchronizers require some friction to work properly. Not wanting to experiment on my own transmission, I drained out $40 worth of RP and refilled it with Mobile I ATF.
Other people posting to this thread have said they've used RP and even synchromesh fluid with no problems.
So, bottom line, yes, the mustang maunal transmission uses automatic transmission fluid. Whether or not you want to use RP against Tremec's recommendation due to unknown compatibility, it's up to you.
Brad
Last edited by 64cv; 03-15-2011 at 08:35 AM. Reason: fat finger
03-16-2011, 05:54 AM
#98
1st Gear Member
Join Date: Aug 2009
Location: NH
Posts: 91
05-10-2011, 09:37 AM
#100
3rd Gear Member
Join Date: Oct 2006
Location: St Louis, MO
Posts: 962
Another satisfied customer of this write up! I changed my fluid this past weekend with no problems at all. I'm just about to hit 100k. The old fluid was pretty ugly. I used 3 quarts of Mobile 1. Stuck my index finger in the hole and it came out wet so I guess thats good enough. No change in shift properties. I think it may be running a bit cooler judging by my stick shift not getting boiling hot anymore. I'll be better able to answer that this summer though.