Thomas S

I'm finally getting my TT and gears installed next week. I have everything but the oil. What kind should I get?

Gearhead

I did get the Mobile 1 75W-140 Synthetic from our local Shucks. It is $19 per quart and you will need two quarts. Do not buy a gear oil with the friction modifier already added and do not add Friction Modifier. Detroit does not recommend this, and it serves no function for the TrueTrac, other than to perhaps reduce lubricity, which you do not want.
Also, make sure you have a nice clean pump to get the oil into the differential fill hole. It is much easier to get the fluid in there, and you don't want to spill stuff this expensive.

Thomas S

Thank you!

Maija

I used Royal Purple oil when I had my Trac-Lock and gears put in. Good luck with whatever you choose, have fun with the car!

garyb900

Jimp, that's great. Let us know how it goes.
I just got my Ford trac-loc and motive 3.73 gears this week and am having it installed next week also! I can't wait to see the difference in my launch.
I have the Royal Purple oil because I needed the friction additives in the t-loc.

Torch_Vert

The Mobil 1 is definitely the way to go. Royal Purple is great stuff, but the friction modifiers are pointless, and possibly detrimental w/ the TT

Thomas S

Ok, went to the local Advance Auto and got some Mobil 1 75W-90. That's all they had, I couldn't remember the last number. Is this ok?

Gearhead

Hi Thomas,
IF you intend to do a change before winter is over and IF you don't plan any continuous trip over 100 miles then I don't see how it could hurt anything. The required viscosity is 75W-140, and this is what you want for long trips and summer use when things get hot and the oil gets thin. Under hot conditions, 75W-90 gets too thin. If you do not intend to change the fluid after 500 miles, then I recommend that you return the fluid and go to another store to get the required viscosity. The Ford recommended fluid can be seen here, on page 230:
http://2006-mustang-gt.com/guides-informat...Owner-Guide.pdf
Let me know how it works out.
Good luck, Brian.

Excepcion13

I put Redline 75W-90 in mine when I got my TT installed. Gearhead gave me the same advice and his advice sounds reasonable. The shop that installed said that 75W-90 is what they usually put in (all they work on is Mustangs), and it was all I had at the time, anyway. So don't stress it, just change it when it gets warmer.

I will drain and fill with the 75W-140 (easy, now, because I have a girdle) when I put my headers and duals on. So far, everything is working just fine (1,000 miles on my TT). Will change in about another 1,000 or so before it gets hot here.

Thomas S

It's probably a good idea to change it after a while anyway, right? I was going to take it back. Maybe I'll just wait to change it when I get my girdle and new axles, muahaha!

Excepcion13

Yeah, I think it IS a good idea to change it. If you haven't installed your TT yet, you might as well put the good stuff in now. As it is winter here and I am limiting my mileage, I am not too worried about it. BUT I will be putting the good stuff in before spring.

New axles? What ARE you planning? You have a MT, if I am not mistaken, right?

Thomas S

Automatic. I dunno, I like to replace the weaks points before they become a problem. The driveshaft is suspect also.

ManEHawke

Brian, can you tell me why friction modifiers are pointless for friction clutch type LSD's?
The guy who tought me told me that you can get glazed or worn discs for too much modifier, but not enough (usually 4-6 to start, but follow OEM) modifier can cause an overheat condition, and can even cause plates & discs to weld together.

Then when you do figure 8''s there should be no tire skidding or chatter.

-Modifier is useless on any other type however (Ramp type, spring type, Viscous coupling type, and ratchet type)

Gearhead

Hi Manny,
You definitely want to use the Ford recommended Friction Modifier with a limited slip differential, and for the reasons that you state above. The Detroit TrueTrac (which is a worm-gear locker and not a limited slip) would not benefit from such an additive. The chat above with Thomas is specifically regarding his TrueTrac.
Sorry about any confusion.
See you later, Brian.

ManEHawke

LOL, I see.
TT as in Detroit's tru-trac, not Ford's Trac-lok (the second T just went over me).

About how much is a Detriot TT btw. I was thinking about an Aubrun Friction Cone type which runs high 300's, but haven't made up my mind.

Thomas S

Hey Brian(Gearhead), one more thing:
http://www.mobiloil.com/USA-English/MotorO..._75W-140LS.aspx
The 140 and 90 both contain friction modifiers according to the website. Is this ok?

ManEHawke

Wow I found the Detroit TT for 382. Not too shabby compared to Auburn (closely priced). Thought they'd be at least in the mid 400 buck range.
feeling pretty good now, if they can be had for lower anywhere else please let me know.

Excepcion13

Got it for 350 @ http://www.drivetrainspecialists.com/ You have to e-mail for details. About the only thing I have gotten a good deal on!!

Heck, my flashy little MMR CAI cost that much.... Bought I before I even took delivery of the car.... It works but I spent about $100 too much compared to other CAIs.

Gearhead

Hi Thomas,
Well, I thought I read the entire Mobil 1 bottle, and I don't recall that it said specifically "this stuff has the friction modifier already added", but your link would indicate that it does. Seems to be built into the part number (LS = Limited Slip). I also found that Castrol makes a 75W-140 too, and it too has the friction modifier already added. Castrol says that it is acceptable for all axles. I guess the claim is that the friction modifier doesn't hurt gear and bearing wear, but that doesn't make too much sense to me. Tomorrow, I'm going to contact the Ford parts guy and try to find out more. The Ford fluid has no index modifier (which the manual indicates) so now I am recommending that you go get the Official Ford Fluid, two quarts, Ford part number XY-75W140-QL, as seen on page 230:
https://web.msslib.dealerconnection.com/Rig...9000c588053025a
See you later, Brian.

FLAstangx3

Kinda late here, BUT, I had heard that you should NOT use a synthetic for the break in period. Hot weather use the 140, colder use the 90. No Friction additive either. THEN, dump it after break-in, and add the proper 140 or 90 synthetic. (Been trying to find the source, I think it was MRT)