Best diff fluid to use

[Stang Lover]

I did do a search but only amsoil popped up.

I'll be doing a gear swap soon after I get my trak lok re-build kit & i'm curious as to what gear oil is the best in your opinion to use. I'm staying away from royal purple as i've read too many negative stories about their products & few positives.

My car is an 01 Bullitt with an IRS.

 

[Norton]

I like Amsoil products. I THINK your car would take their Severe Gear 75W-90.

 

[GregFloresSVT]

I'm going to switch to all amsoil oil around christmas time.
For now I rebuilt my rear end and had gears installed, I filled her up with Royal Purple no problems yet and looked good to me after 500 miles when i replaced the oil again with RP

 

[Stang Lover]

I like Amsoil products. I THINK your car would take their Severe Gear 75W-90.

I'll probably give them a try. I put their tranny ATF fluid in my car but couldn't really tell a diff b/c my TOB was sheared so I cant say it was good. Does mobil make any gear oil?

 

[Norton]

Does mobil make any gear oil?

Yes... Mobil 1 Gear Lubricants

 

[UnleashedBeast]

Severe Gear 75W-90 is correct.

Anyone who wants to buy anything from Amsoil should chat with me first to buy at cost. Do not pay internet retail prices shown on the website.

 

[Jimmysidecarr]

I did do a search but only amsoil popped up.

I'll be doing a gear swap soon after I get my trak lok re-build kit & i'm curious as to what gear oil is the best in your opinion to use. I'm staying away from royal purple as i've read too many negative stories about their products & few positives.

My car is an 01 Bullitt with an IRS.

You need to take those negative stories with a grain of salt, many have not been properly diagnosed and it's easiest to just blame the oil.

There isn't a 75W-90 gear oil on the planet that has higher film strength than Royal Purple Max Gear 75W-90 (part #01300, quart bottle).

Ferrari's race team in Europe runs that same exact product in their race cars. The production cars do get a different fluid though due to licensing agreements with certain oil companies.

I've been running Max Gear in 04 Cobra since 2005 and have done lots of road race style track events without an oil cooler. It works great!:beer:

 

[UnleashedBeast]

There isn't a 75W-90 gear oil on the planet that has higher film strength than Royal Purple Max Gear 75W-90 (part #01300, quart bottle).

Not possible sir! It took days for me to wash off the lubricant I found in the girlfriend's nightstand top drawer.

:-D

 

[MJN]

:lol: That one made me laugh

 

[Im1livewire]

Not possible sir! It took days for me to wash off the lubricant I found in the girlfriend's nightstand top drawer.

:-D

+1 He's witty, that Troy!! :beer:

 

[masonh]

It took days for me to wash off the lubricant I found in the girlfriend's nightstand top drawer

Astrolube for the rear diff?

On a serious note, while I wouldn't put Royal purple in the engine, I have heard their 75W-90 is as good as it gets from many different and knowledgeable sources. I'm changing mine out when i get to 1000 miles and I am either using the RP, Motul 300 Gear or the new Millers that i hear is very good too.

 

[03Cobranator]

I use the Lucas Gear Oil and havent had any issues. They didnt have 75w-90 so i went with the closest option they had I forget exactly what it is but it was a little thicker. What I really like is my gears used to whine and now they are MUCH quiter. I didnt think oil would make a difference but ill take what I can get lol

EDIT: Royal Purple is what I had in it originally.

 

[NasteeNate]

I've used the Amsoil gear oil. Its been in my diff for about 3yrs plus after the rebuild. The diff runs cool and strong! Its so quiet I can hear my trans over it when im cruising on the street.

 

[oldmodman]

Not possible sir! It took days for me to wash off the lubricant I found in the girlfriend's nightstand top drawer.

:-D

How were you able to get the purple color off of it?

 

[MBoyle1]

Any friction mod needed for the amsoil or RP?

 

[Jimmysidecarr]

I use the Lucas Gear Oil and havent had any issues. They didnt have 75w-90 so i went with the closest option they had I forget exactly what it is but it was a little thicker. What I really like is my gears used to whine and now they are MUCH quiter. I didnt think oil would make a difference but ill take what I can get lol

EDIT: Royal Purple is what I had in it originally.

A 75W-140 is a heavier fluid and is therefor better able to dampen gear noise than a 75W-90 fluid... not matter what oil company you use.

Lighter oils transmit more noise.

03/04 Cobras call for a 75W-140 not a 75W-90.:beer:

 

[Jimmysidecarr]

Any friction mod needed for the amsoil or RP?

All Royal Purple Max Gear oils already includes an appropriate dose of LSD FM, (limited slip friction modifier):beer:

 

[03SonicBlueGT]

So would adding the bottle of friction modifier (with the RP fluid) anyways, hurt anything? :shrug:

 

[DHG4410]

Synergyn

 

[RedRocketMike]

Jimmy, do you have any data on increased parasitic loss between 140 and 90?