Rear Diff Fluid

['94IDITurbo7.3]

I would like to change the gear oil in my diff sometime soon.

i did a search on here and came up with amsoil, royal purple, & mobile 1.

i will be using synthetic. does the synth come with the friction modifier already in it?

any other opinions on brands of fluid?

What weight lube do i use?


thanks

 

[CDX825]

Most of the time you shouldn't need a friction modifier with a true synthetic.

I would recommend Amsoil. Royal purple is good to but its about twice the price.

 

[RANOVRU]

Ive always used 80/90 weight.

And if you know you have a limited slip I would use something like this as well along with the diff oil.

You must be registered for see images attach

 

[OLDBULL8]

Ya want to use 80/140 synthetic. All 4:10 are limited slip, unless changed to a locker. Use the additive also.

 

[02x72]

I run Lucas in mine, 80/90. Put it in about a year ago and checked it a few weeks ago, seems to be holding up well.

 

['94IDITurbo7.3]

Ya want to use 80/140 synthetic. All 4:10 are limited slip, unless changed to a locker. Use the additive also.

80 or 75? all i have seen in my brief research has been 75. i will keep looking though. the synth oil says that it has the ls additive already in it.

 

[PwrSmoke]

With a few exceptions, syn is 75W and dino is 80 or 85W... because the syn has better cold flow. If you don't have a LSD, best not to buy an oil with the LSD friction modifier (FM) in it. Many of them are organic in nature and don't stand up to heat well. High heat causes them to oxidize and it brings the oil down with it. Some syno oils have good enough friction characteristics that they don't need any FM.

Best to base oil viscosity choices on how you use the truck. If you tow hard and alot, your diff oil will get very hot and you should use a 75W140 syn or an 85W140 dino. If you don't tow often, that 140 grade oil can cut into fuel economy (because the oil never gets hot and it stays thick and causes drag). I have a diff oil temp gauge on my truck now, as well as a Mag-Hytec cover, which helps it run cool. I on run a 90 grade oil (LE-607 from Lubrication engineers... no longer made but I have a large supply).

Because you live in Michigan, and it gets cold there I would point you to a 75W90 syn or a 75W140 if you tow alot. I'm not a big syn oil guy when it comes to engines but with gear oil, it makes a difference. Brand... not so important (to me... I'm not a one brand guy).

 

['94IDITurbo7.3]

i don't tow with my truck and if i ever did it is not heavy. i just daily drive it.

so based on my use you would say the 75W90 synth?

 

[FORDF250HDXLT]

im running this front and rear;
http://www.mobiloil.com/USA-English...bil_1_Fully_Synthetic_Gear_Lube_75W-90LS.aspx

 

['94IDITurbo7.3]

im running this front and rear;
http://www.mobiloil.com/USA-English...bil_1_Fully_Synthetic_Gear_Lube_75W-90LS.aspx

that is the same stuff i just found on advance auto's site. i think i will visit my friends at car quest sometime and see what there prices are.

 

[FORDF250HDXLT]

dont forget to use coupon code: VISA
during checkout.
( keep code: P20 handy when buying more/higher priced stuff.)

 

['94IDITurbo7.3]

how much fluid do i need?

 

[Optikalillushun]

im running this front and rear;
http://www.mobiloil.com/USA-English...bil_1_Fully_Synthetic_Gear_Lube_75W-90LS.aspx

Same here, no isses in either of my older trucks. Also use Mobil 1 Syn ATF in my t-case n ZF.

 

[93f250idi]

Ya want to use 80/140 synthetic. All 4:10 are limited slip, unless changed to a locker. Use the additive also.

mine aint ls

 

[Optikalillushun]

how much fluid do i need?

i think its 7.5 pts.