Changing manual transmission fluid in my 2005 Mustang GT. Can I use oil?

craven · 10-14-2009

i am thinking about using castrol syntec 0w20 or 5w30 in the tranny...is this good? or should i use the mercon V synthetic?

alot of people say 0w20 shifts way smoother...

partsbill · 10-14-2009

I think I would stick with what Ford recommends,
MERCON® V Automatic Transmission Fluid

Alfaduetto · 10-14-2009

I put Royal purple manual trans fluid in my '08, didn't seem any different than the factory fill. The friction improver package in Mercon 5 does make the syncros work better and last a little longer, don't think engine oil has the right sliding friction characteristics since they removed the Zinc for flat tappet lifters.

craven · 10-14-2009

i see on this printout from ford that i have the 3650 tranny with 355 gears, and that it recommends, the mercon V synthetic...

i guess i will use that...

MaverickMLFD371 · 10-15-2009

I use the Royal Purple stuff.

topbliss · 10-15-2009

+1. I did not see any difference using RP over the factory fill fluid

Quote:

Originally Posted by Alfaduetto

I put Royal purple manual trans fluid in my '08, didn't seem any different than the factory fill. The friction improver package in Mercon 5 does make the syncros work better and last a little longer, don't think engine oil has the right sliding friction characteristics since they removed the Zinc for flat tappet lifters.

**stlwagon** · 10-15-2009

Never use motor oil in a transmission or differential.

craven · 10-16-2009

i am thinking about rp syncromax....

dysan · 10-16-2009

Royal Purple Syncromax all the way. I contacted Tremec directly and they said you can put syncromax(based on GM's syncromesh) in these trannies to smooth/quiet them down. I've been running it in mine for approx 40k miles now.

**stlwagon** · 10-16-2009

I run Amsoil synthetic in mine.

mustangdave2008 · 10-16-2009

I've read the RP synchromax makes the shifts a little smoother. Did you notice that dysan?

Itchy · 10-16-2009

Quote:

Originally Posted by stlwagon

I run Amsoil synthetic in mine.

It's sitting on my shelf, just waiting for me to have time to drain and refill.

topbliss · 10-16-2009

NO change in mine using this.. works fine but no better then the factory fill

Quote:

Originally Posted by mustangdave2008

I've read the RP synchromax makes the shifts a little smoother. Did you notice that dysan?

craven · 10-19-2009

put syncromax in today, i drained old fluid out, but not a complete dry drain...it was slowly dripping out and closed it up and put in 3 quarts of syncromax....its about half a inch from the fill hole...

smoother shifting for sure....its very nice...

it was priced at 18.99 so i told the cashier that it was ridiculous and so he sold it to me for 12.00...LOL