Gear oil for the rear end

[nmikmik]

I am not sure what gear oil to use in my TC. I went to wallymart and bought a gallon of Supper Tech gear lubricant SAE 85W-140 GL5 (on the hunch :eek:) The manual says XY-90-QL & I have no clue what it means... I don't want to assume anything, so do you know if it's compatible? I don't mind exchanging it or even getting a synthetic oil like AMSOIL - for the same price :o

[LithiumCobalt]

I actually just did this job last week. Here's my two cents...The buck-toothed parts counter guy at the Ford dealer said 75-140 was the correct oil. After looking at the service manual for my '96, it said 80/90. I went with Valvoline 80/90 Durablend which has some conventional and some synthetic oil mixed. Don't forget a tube of silicone gasket sealant. If you have any questions, I'd be glad to help you out.

[Hensley]

Did you drop the cover or use a suction pump? I know the best way is to drop the cover and really clean everything out, but both get the job done.

[megaforcer]

80W90 has been superseded by 75W140 which is a fully synthetic fluid at 20 bucks a quart. Ford now uses only 75W140 in all their differentials.

[LithiumCobalt]

Did you drop the cover or use a suction pump? I know the best way is to drop the cover and really clean everything out, but both get the job done.

I unbolted the cover, which wasn't too hard at all. Cleaned it up and reapplied the sealant to make sure I wouldnt have any leaks for a long time.

[LithiumCobalt]

80W90 has been superseded by 75W140 which is a fully synthetic fluid at 20 bucks a quart. Ford now uses only 75W140 in all their differentials.

Damn, I thought the parts guy was full of shit. He knew what he was talking about afterall. I noticed that it was fully synthetic. I think he said it was around $5.49 a quart. Maybe I will change it out again just for shits and giggles.

[megaforcer]

The only reason the parts guy told you it takes 75W140 is because thats the only thing he has available :D You cant buy 80W90 anymore from Lincoln dealers.

I bought some in May of last year and the list price was $18.37 a quart. Now its close to $20.

http://silvercrosscars.com/lol/145.jpg

[nmikmik]

Thanks guys! I don't see any reference to the oil been synthetic on the container... I assume they (the manufacturere, i think Quaker State) would be using every opportunity to trumpet that fact if it would have been. So for 8.88 how much synthetic can I buy :D

[ALPHA1906]

i suggets 80-90 i used motorcraft and one bottle of 90-140

[ALPHA1906]

u can but it from the lincoln dealer that where i got mine. only paid 4.99 per bottle

[93cartiertc]

If not Amsoil 75w-90 Mobil 1 is good Valvoline 75w-90 is good too! Even the Dura-lube by Valvoline at 80w-90 is good. I picked up a gasket for mine. Do these filler plugs get rusted up badly, or is it more simplier than that? I was under the impression that 85w-140 was good as a top off addition, but that full strength might cause some gear chatter, especially during the frigid cold months, as wel as increase gas mileage? Thanks in advance!



1993 cartier tc 260,000
1995 sig tc 110,000
Both have original miles.

[LithiumCobalt]

If not Amsoil 75w-90 Mobil 1 is good Valvoline 75w-90 is good too! Even the Dura-lube by Valvoline at 80w-90 is good. I picked up a gasket for mine. Do these filler plugs get rusted up badly, or is it more simplier than that? I was under the impression that 85w-140 was good as a top off addition, but that full strength might cause some gear chatter, especially during the frigid cold months, as wel as increase gas mileage? Thanks in advance!



1993 cartier tc 260,000
1995 sig tc 110,000
Both have original miles.

Drain plug is easy to get off. Get the rearend up on jack stands, crawl under and on the forward-facing side of the differential, stick a 1/2" ratchet in the square hole and give it a little crank. The outside will look pretty rusted up, but it will come loose.

[nmikmik]

Guys I am still confused because I don't know how to read gear oil weights. Is it similar to the engine oils where the first number represent oil viscosity cold and the second number same oil but warmed up to the operating temperatures? If that is the case why would manufacturer switch from one weight to another?
quote:
80W90 has been superseded by 75W140 which is a fully synthetic fluid at 20 bucks a quart. Ford now uses only 75W140 in all their differentials.

I bet it would cause major chatter with heavier oil.

[megaforcer]

Synthetic oil is much thinner, thus 80W90 conventional goo would be equivalent or close to 75W140 synthetic.

[nmikmik]

in case it wasn't confusing enough:
http://www.redlineoil.com.au/Uploads/Downloads/tech%20dataweb%20gearlube2%20Aust.pdf

I guess my assumption about viscosity was wrong ha :achoo:

[nmikmik]

here is another site specifying 75 W90 - i trusted AMSOIL for a long time & haven't had a reason to change my opinion on it yet. I am going with 75 W90 conventional and then if I like it I'll change it to synthetic after couple of thousand miles. my 2c.

http://www.amsoil.com/scripts/runisa.dll?amsoiloaf:index

[Chevyguy]

I just filled with Valvoline conventional 85W-140 and can report at least 1-2 MPG drop over about 3-4 weeks now. Itching to replace with some synthetic 75W or 75W-140

Seems like the recomendations for the rear visc is all over the map

[Jerry in Pitt PA]

Mechanics will say "gear oil is gear oil, its all the same"
But when I changed the rear end gear oil in my 93 TC I used 80-90 Durablend AND I added a bottle of the Ford additive you have to get at the dealer.

Jerry

[gadget73]

gear oil is gear oil for the most part. The only time you need the friction additive is if you have a traction lock. It does absolutely nothing on an open rear. The bigger atvantage to the synthetic is that it flows better when cold, and in the winter will give a *slight* economy increase as a result. It probably also protects the parts a bit better due to the improved flow characteristics.

[Dereck]

80W90 has been superseded by 75W140 which is a fully synthetic fluid at 20 bucks a quart. Ford now uses only 75W140 in all their differentials.

Damn, I thought the parts guy was full of shit. He knew what he was talking about afterall. I noticed that it was fully synthetic. I think he said it was around $5.49 a quart. Maybe I will change it out again just for shits and giggles.

Hi

I wish I only had to pay $20 for 70w/140 , here the only place you can get it is from Ford at $40 a quart :)

Regards

Dereck

[Jerry in Pitt PA]

I thought that you should add the ford friction modifier/additive if the rear end is limited slip.
Any comments?

My 93 TC get 27 mpg at 68MPH, great economy car! 161K miles and purrrrs like a kitten! Never had a car this old what so many miles that look and rides so good!!!

Jerry

[gadget73]

limited slip = traction lock. Yes, those need the additive. Many don't have a traction lock unit though, so the friction modifier isn't always neccesary.

[Sixlitre]

I just filled with Valvoline conventional 85W-140 and can report at least 1-2 MPG drop over about 3-4 weeks now. Itching to replace with some synthetic 75W or 75W-140

Seems like the recomendations for the rear visc is all over the map

Between your testimonial and the advertizing hype from Royal Purple

I'm expecting miracles tomorrow !

All kidding aside I've used the Mopar fully synthetic in my Bronco's axles for years. This time I'm gonna stick the Royal Purple stuff in the TC and see if I feel a difference;

http://www.supermotors.net/getfile/238004/fullsize/img_0109.jpg

http://www.supermotors.net/getfile/645571/fullsize/img_0023.jpg

BTW I used to add friction modifier to the front axle of my bronco (not knowing if it was limited slip, like the rear), it does no harm.

Sixlitre