Engine/Transmission (1994 - 1998) rear axle lubricant

[SRehberg]

I'm getting ready to change my rear axle lube over to full synthetic, and wondered about two things; do you need to put the additive in for the limited slip clutches and do you still change out the lube at the specified intervals? If you do the same change out, it seems like it would get pretty expensive. I plan on towing a 5th wheel on a long trip, and I understand the synthetic is the only lube to use; is it that much better than 85-140? Thanks

 

[LSMITH]

There is really no good answer for the modifier or not, some lubes need it and some do not. Some trucks get by without it and some need it. What oil are you going to use? That would help a ton.



The synthetic is the way to go for the rear, and if you tow a lot or tow heavy often I would put in a 85w-140 synthetic. If you only tow occasionally I would just put in a 75w-90 synthetic.



Hope this helps.

 

[Boldt's Wagon]

The Redline 80W-140(?) has the limited slip additive included.

 

[SRehberg]

I had planned on using the Valvoline brand, but I am open to others, including the Red Line products. I know our local diesel distributor handles that line. I noticed Mobil 1 only comes in the 75w-90 weight, so I kind of lean towards the 80w-140. I guess because I have been using it. I started using that weight, as my neighbor is the supervisor for our City fleet of vehicles, and mentioned the police were tearing the rearends out of the cars right and left, then they switched to the 80w-140. The incident of rear end failures according to him dropped dramatically. That is the only thing that prompted me to change to a heavier weight.



Regarding the frequency of changing the oil, can I go longer than specified, or is it the same schedule? Right now I change out the petroleum stuff every 20K.



Thanks to everyone for the help.

 

[LSMITH]

If you can get the Valvoline brand in the weight you want there is nothing wrong with it, I would use it in my truck without a doubt. I use the Mobil 1, in 75w-90. Mobil makes a 85w-140, but the only place I have ever seen it is at the distributor. I have also only seen 3 gallon and larger containers. I would go at least 40K on the synthetic, and lean toward 50K. You can sample it too, at say 25K miles to see what the health of the oil is if it would make you more comfortable in the longer drain interval. I know looks are not a good indicator of oil health, but my Mobil 1 75w-90 looks great with over 50K miles on it. I will change it out this summer and sample it to see what condition it is really in.

 

[SRehberg]

LSMITH, thanks for the information. Did you have to use the additive for the limited slip unit with the Mobil 1?

 

[SlyBones]

Like LSmith said, some need modifier and some dont.



After doing the change go out and do tight figure 8's in an open parking lot and pay attention to chatter. If it seems OK, drive it for a few days and see how grabby it feels going around corners. If you end up adding some add it in 2oz increments. Do the figure 8's and then drive and see how it feels. Dont just pour a bunch in.

 

[SRehberg]

Thanks for the info on the additive. I hate using that stuff anyway, as it smells terrible. I don't know what it's made of, but you would think it could smell a little better! Sounds like Red LIne has taken the guess work out of it by adding it right off. Have you noticed an improvement over the regular hypoid?

 

[amsoilman]

I had the Amsoil Series 2000 75W-90 synthetic gear lube that I use analyzed at 60,000 miles and it was found to be in excellent condition. Visc. was 15. 2@100 C. OXD was 4. 4 %. In most cases this lube does not need a modifier for LSD's. According to spec. sheets, this lube has a Visc. of 15. 7@100 C. when new.



However, whenever one changes gear lubes, it is advisable to drive the vehicle in "tight" figure 8's as someone else has suggested.



Wayne

amsoilman

 

[SRehberg]

Amsoilman, thanks for the post; sounds like the lube is holding up well, but you didn't mention if the truck is running solo or pulling a trailer. I don't know if this would make much difference, but with 60K on the oil, that seems great! One question I forgot to ask, out in the brake drum hubs there is oil that won't get removed unless the hubs are removed. Any problem with compatibilitiy? Thanks once again

 

[kscheffler]

Rehberg: How did the redline work

Rehberg: Did you add Redline and how did it work? I am changing out my gear lube and trying to figure out what I am going to use. Did you use the redline with the slip additive? Thanks in advance for any info... kts

 

[SRehberg]

I haven't changed the fluid yet, as I have a bigger problem going. My transmission is sick at the moment, so the vacation with the trailer (reason for axle lube change) is out of the question. I still plan on changing it, but I can't help you with first hand info... . sorry. I'm trying to get the stealer to stand behind their trans overhaul, but they are ignoring me for now. Wrong thing to do! They rebuilt it 3 times, and it still has an appetite for metal!

 

[amsoilman]

SRehberg,

I pull mostly in the summer. I have a 25 ft cruiser and a couple of watercraft I usualy pull behind the boat.



The Amsoil gear lube is compatable with petrolium products, so there is no problem in capatability.



Wayne

amsoilman

 

[amsoilman]

SRehberg,

I pull mostly in the summer. I have a 25 ft cruiser and a couple of watercraft I usualy pull behind the boat.



The Amsoil gear lube is compatable with petrolium products, so there is no problem in capatability.



Wayne

amsoilman

 

[amsoilman]

SRehberg,

I pull mostly in the summer. I have a 25 ft cruiser and a couple of watercraft I usualy pull behind the boat.



The Amsoil gear lube is compatable with petrolium products, so there is no problem in capatability.



Wayne

amsoilman

 

[Pit Bull]

I think I am going to give Royal Purple a try, just because it is so hard to get. It will make it seem special

 

[amsoilman]

This is what Noria Corp had to say about synthetics.

"The advantages offered by synthetic oils are most notable at either very low or very high temperatures. Good oxidation stability and a lower coefficient of friction permits operation at higher temperatures. The higher viscosity index and lower pour points permit operation at lower temperatures. "



"Many synthetic lubricants offer one benefit that mineral- based lubricants typically do not. Energy savings due to the lower frictional characteristics of certain synthetics can be found to be as high as 5-10 percent. This is significant considering the approximate annualized cost of $25,000 in electricity for a 150 hp (112 kW) compressor. "