Gear Lube Choices

[SlyBones]

For the rear end of my truck. 3. 54 LSD Dana 70. Looking for full synthetic choices. Pro's and Con's of 70w-90 versus 70w-140.

 

[Cooker]

Daily driver only or are you towing something?

 

[LSMITH]

Sly, mine is a daily driver and I mainly hot rod around. My towing is mostly light stuff.



I changed from the dino 75-90 to Mobil 1 75-90 in both diffs and am really happy with it. I picked up over 1 MPG on my commute which is about 45 miles each way. If you drive short distances I don't think you will realize much if any gain in economy. The temp of the rear diff at both ends of the commute dropped 20 degrees too, so there is definitely less friction. Hope this helps.

 

[Briar Hopper]

I'd go with 75W-90 unless you're towing ALL the time. It flows better in cold climates, and still offers all the protection you'll need. The 140 is a bit thick, overkill except for sled pullers and hotshots.

 

[SlyBones]

90% daily driver, 10% towing 8000#.

Currently using 75w-90 weight.



A search here yieled:

-- Amsoil series 2000

-- Royal Purple

-- Mopar

-- Mobil 1

-- Valvoline

-- Lubrication Engineers



Called Lynnwood dodge, wanted $19. + per qt. for the Mopar stuff. Wonder when the last time they sold one of those. Gonna go by NAPA on the way home.

 

[LSMITH]

Sly, if you are not aware some (me included) have had problems getting the LSD chatter to go away with friction modifier other than the Mopar stuff. The dealer has it on the shelf and it worked a world better for me than any other brand I have tried. Lots of the Amsoil guys report not using any modifier. I definately needed it with the Mobil 1. Hope this helps.



I have also seen on here several guys using the Valvoline full synthetic that has the modifier already in it, all reports I remember were good.

 

[SlyBones]

LSmith,



I am currently using Amsoil series 2000 75w-90. I used 3oz to get the chatter to go away. -- Thanks.



I had heard that our diffs require about 6%-8% modifier in there for proper operation. Based on a stock pan this is about 8oz or 2 bottles. With a mag-hytec you may need more. Amsoil was supposed to be about or equivelant of 5% for example. So depending where your diff falls on the scale you may or may not need to add some. And if you need to add some it may vary depending on what pan you have.

 

[Briar Hopper]

You left out LE, Lubrication Engineers, SlyBones. I believe they also make a good synthetic. I use Amsoil myself. No leaks, no friction modifier. No metal shavings on the little magnet end of the dipstick in the Mag-Hytec, since switching to Amsoil in the axles.

 

[C Schomer]

I like the RP Maxgear 75w90 better than the Ams 2k 75w90. Needed modifier with Ams but not with RP. Developed ring and pinion noises with Ams - it went away after the RP was in there for awhile.

 

[BigMike]

I'm thinking of doing this. My manual says 75-140. Is it ok to use something different from that? Do I need the sticker if I don't have LSD?

 

[Ted Constantine]

I just changed both axles over to Amsoil 2000 75w90 last week. The rear end needed no modifier and every thing is working well. I don't know that it has changed anything in terms of performance.



Ted

 

[RustyJC]

Since we tow a 13,500 lb 5ver, I changed out to Royal Purple 85w-140 synthetic. This lubricant already has friction modifier in its formulation, and I've had no LSD chatter at all since the changeover - no Mopar friction modifier added. It definitely runs cooler and quieter with the synthetic.



Rusty

 

[paccool]

RP 85-140 here also. Don't tow that often but it's covered when I do. Had Eaton synthetic in for a short time but had chattering problems even with additive. I added a bottle with the RP just to be sure every thing would work alright.