Differential Oil

[CarbonSteel]

I am running Amsoil 75W-110 in the front axle because that oil is the viscosity that 75W-90 used to be before the J306 tables were updated some time ago. I run 75W-140 in the rear for heavy duty use such as towing. I have the M210 front and M220 rear.

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[jeepdabest]

I am running Amsoil 75W-110 in the front axle because that oil is the viscosity that 75W-90 used to be before the J306 tables were updated some time ago. I run 75W-140 in the rear for heavy duty use such as towing. I have the M210 front and M220 rear.

Do you use the Mopar Friction Modifier?

 

[CarbonSteel]

Do you use the Mopar Friction Modifier?

No, I have ELD differentials so FM is not needed, but Amsoil also has some FM in it.

 

[jeepdabest]

No, I have ELD differentials so FM is not needed, but Amsoil also has some FM in it.

Should I use it in my LSD? Many say not needed because it's added in many formulations?

 

[CarbonSteel]

Should I use it in my LSD? Many say not needed because it's added in many formulations?

You could always try it, but if you experience chatter while turning at low speeds you will need to add some to stop it.

 

[1quick1]

I'm getting ready to do mine and got

Valvonline synthetic 75W-90 for the front D30
Valvonline synthetic 75W-140 for the rear D44 w/trac loc (LSD)

I also got a 4oz bottle of the Mopar friction modifier. The Valvoline synthetic has FM in it but I can't seem to get a clear answer if it sufficient or if the Mopar stuff is needed.

 

[jeepdabest]

You could always try it, but if you experience chatter while turning at low speeds you will need to add some to stop it.

Thanks for the quick reply!

 

[jeepdabest]

I'm getting ready to do mine and got

Valvonline synthetic 75W-90 for the front D30
Valvonline synthetic 75W-140 for the rear D44 w/trac loc (LSD)

I also got a 4oz bottle of the Mopar friction modifier. The Valvoline synthetic has FM in it but I can't seem to get a clear answer if it sufficient or if the Mopar stuff is needed.

Sounds exactly what I'm going to do! I"m assuming we just dump the whole bottle in? Will too much hurt?

 

[1quick1]

Sounds exactly what I'm going to do! I"m assuming we just dump the whole bottle in? Will too much hurt?

My understanding is you dump the whole 4oz bottle in first then fill the differential oil.

I'm also curious if there is a risk of running too much. I've ready every differential oil thread on this forum and haven't completely found out although there have been some to say to put the Mopar FM in and some saying they just use the FM that came in the oil without issue.

 

[CarbonSteel]

My understanding is you dump the whole 4oz bottle in first then fill the differential oil.

I'm also curious if there is a risk of running too much. I've ready every differential oil thread on this forum and haven't completely found out although there have been some to say to put the Mopar FM in and some saying they just use the FM that came in the oil without issue.

Yes, you can add too much. Too much FM can make the diff act like it is "open" because the clutches will slip too much. Keep in mind these differentials have a very small capacity (1.3Qts in front and 1.5Qts in rear--at least mine did) and 4 ounces will be about 8% of the capacity in the rear and about 10% in the front.

I would add 2 ounces to start and add more if chatter is experienced.

 

[jeepdabest]

Yes, you can add too much. Too much FM can make the diff act like it is "open" because the clutches will slip too much. Keep in mind these differentials have a very small capacity (1.3Qts in front and 1.5Qts in rear--at least mine did) and 4 ounces will be about 8% of the capacity in the rear and about 10% in the front.

I would add 2 ounces to start and add more if chatter is experienced.

Thanks for that! Should I only be worrying about it in the rear dif?

 

[1quick1]

Yes, you can add too much. Too much FM can make the diff act like it is "open" because the clutches will slip too much. Keep in mind these differentials have a very small capacity (1.3Qts in front and 1.5Qts in rear--at least mine did) and 4 ounces will be about 8% of the capacity in the rear and about 10% in the front.

I would add 2 ounces to start and add more if chatter is experienced.

You're correct, I should have clarified you can put too much. I guess the mystery is not knowing how much is in the Valvoline oil. I'm thinking next time I'll get it without FM so when I add it I know I have the correct amount.

Thanks for that! Should I only be worrying about it in the rear dif?

Yes, only on trac-lok (LSD/anti-spin) which is only in the rear.

 

[CarbonSteel]

Thanks for that! Should I only be worrying about it in the rear dif?

If both axles are LSD, then you will need it in the front axle as well. However, obviously the rear axle is in 100% continuous operation and it will be the one you notice making the noise more often than the front which is only used in 4x4 conditions.

 

[oceanblue2019]

Yes, you can add too much. Too much FM can make the diff act like it is "open" because the clutches will slip too much. Keep in mind these differentials have a very small capacity (1.3Qts in front and 1.5Qts in rear--at least mine did) and 4 ounces will be about 8% of the capacity in the rear and about 10% in the front.

I would add 2 ounces to start and add more if chatter is experienced.

^^ This. Too much FM can be a bad thing. With most gear oils containing FM I'd actually go without and see if you get chatter. If yes add 1 oz at a time until the chatter stops.

 

[jeepdabest]

^^ This. Too much FM can be a bad thing. With most gear oils containing FM I'd actually go without and see if you get chatter. If yes add 1 oz at a time until the chatter stops.

Thanks! Is 'chatter' a metallic sound?

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