Engine/Transmission (1994 - 1998) Limited slip rear

[SRehberg]

I know this subject has been on here before, but it seems like there has not been a firm answer that I have seen. When changing over to the Amsoil 75w-90w in the rear end of a Dana 70 with the limited slip unit, does the modifier have to be added or is it just good sense to put it in anyway?



What should the going price for a gallon of the oil run? I went to check the price tonight and it was running about $6 qt. in the gallon jug.

 

[Dennis Garrett]

Don't expect the Synthetic 75-90 to last you forever. I decided to try and run mine 100k on Amsoil 75-90, big mistake. The carrier bearing on the right side went out, and the powered bearing grit in the oil ruined the pinion bearings, & all four wheel bearings. Whatever kind of oil you use, change it when the owner's manual tells you to. In 170k miles total, I've changed mine several times, and it will always chatter unless I use the Mopar additive. Nothing else seems to work in mine. After the rebuild, I went to Royal Purple 85-140 (I think). It said it already had the additive, but it chattered anyway until I added the Mopar stuff. Same with Champion additive, it didn't work in mine.

 

[Dan_69GTX]

Anyone know the part number for the Mopar additive?



Thanks!

Dan

 

[Kirwin]

MOPAR LS Additive

Part # is 04318060AB Ken Irwin

 

[SRehberg]

Did the Amsoil fail due to lack of changing it, or was something in the rear end dying that distributed material throughout causing bearing failures everywhere? I'm concerned, as I do change per service manual schedule, but it's been with the conventional oil up to now. I was going to change to the synthetic due to the manual calling for synthetic when towing fairly regular.



I wonder how many trucks (all brands) that are running around that have never seen a rear end oil change. I've seen some that the oil came out looking like black paint, but still seemed to be operating o. k. They probably don't see the torque that our trucks do, for that matter.



Is Amsoil good to use, or should I be looking for another brand?

I just want the rear end to go a LONG time if possible.

 

[Gary - K7GLD]

Amsoil - nor ANY good synthetic can offset or comphensate for the natural wearing of clutch packs in a LS differential - and the damaging contamination that wear can bring with it. Sure, older, non-LS differentials would frequently outlast the vehicle they were installed on with NO lube changes - but those weren't LS differentials, either...



Best to observe the suggested manufacturers service recommendations!

 

[Extreme1]

Back on topic...

I installed a limited slip several monthes ago using Amsoil and no additive. After a couple thousand miles it chattered. I bought the additive and decided I'd add 1 ounce at a time until it stopped. I added 1 ounce and it stopped!



I have the MagHytech cover on a Dana 80 and it holds 2 gallons of lube.

 

[Gary - K7GLD]

I just installed the Amsoil 75/140 stuff in my LS differential (6000 miles on truck) - no trace of chattering so far - would almost prefer at least SOME indication of LS activity, even if it does mean I gotta add some additive - at least then I'll have evidence the LS is working as expected... Time will tell...

 

[SRehberg]

Which weight do you recommend? I see one post installed the 75-140W; would it be better than the 75-90W for pulling trailers? I'm currently running the 75-140W regular stuff, and the reason I'm doing that, is my neighbor. He's in charge of the City Police fleet, and he says since they changed the rear end lube from the 75-90W to 75-140W, they have had a drastic drop in rear end failures. He states if the cops can't tear up the rear ends, then it's a good test! I know the synthetic is different, and the clutch packs have narrower spaces to get lube into, so which is recommended? Thanks

 

[Kirwin]

75W -140 regular stuff

Are you running the MOPAR 75W-140? Its synthetic. My rear end runs close to 200 F towing at 75 F ambient. I was quite surprised but it was backed up here on the TDR website that that is normal temp for a loaded truck pulling a trailer hence Dodge's owners manual's recommendation to change to the synthetic lube for the differential

 

[SRehberg]

I want to change to synthetic, but presently I have Valvoline conventional oil in the rear. I haven't been pulling a trailer up to now, but this spring/summer we will be pulling a 5th wheel. I'm surprised at the temp that the rear runs, but I guess there's alot of load on the gears/bearings. I found in the owner's manual where it recommends the 75-140W synthetic; they hide it in a different section than the lube section.



How does the Mopar compare in cost vs. the other brands?

 

[Kirwin]

Mother Mopar's rear end lube

On 10/17/02 it cost me $15. 20/quart at the Dodge dealer. List price is $19. 00. Part number 04874469. Couldn't tell you what other brands cost as this is the only one I have used so far. With the Mag-hytec cover my differential holds 5 quarts. So Far I have been changing it every 15K miles. My truck was purchased to haul the trailer so most of my miles are towing. It still looks like new at that change interval. I was surprised at the temp too but after searching the TDR web, it seems to be about average. Some members have seen a little higher on long hills in hot ambient conditions. Seems to be mostly affected by speed though, difference between steady state 62 MPH and Steady state 72 mph is 25 F. Hope this helps Ken Irwin

 

[SRehberg]

Thanks for the reply, and I can see the synthetic is the only way to go. Here in California, the towing speed is 55mph, but I don't think to many adhere to that. The price per quart is cheap compared to replacing the rear end! I've been changing my oil every 20k, but I guess I should shorten that interval, as I see severe duty is 12k!

 

[Kirwin]

Service Interval

The oil doesn't wear out just like engine oil doesn't wear out. It becomes contaminated with corrosion and wear products. The limited slip rear end just adds to it with more wear particles from the clutch pack in the differential. The Mag-Hytec cover has a magnetic dipstick that helps also. The drain plug is a great advantage! Every rear end should have a drain plug in my opinion. Ken Irwin

 

[SRehberg]

I understand about the drain plug, it would sure be nice, as there aren't to many products that stink like the hypoid with the additive in it! D/C probably saved 5 cents a truck leaving the drain plug out. The Maghytec pans are nice, but kind of pricey it seems, but everything else is too nowadays. The extra quart would be nice for extra cooling.