Gear Oil in rear end

[welder]

What oil do you guys run in your Mopar rear ends, I have the 11 1/2" RE in my 2500HD and am looking at Royal Purple gl5 85W140

[pjay9]

I use a syn gear oil...don't know what it is as the bottle is in the garage in Tacoma, I am in The Cape May, MD area. Syn has about 65000 on it now and looks good when I checked before this trip. I did the change when I replaced the gear cover. I suspect it runs cooler but no temp gage to say so...just my gut feeling. Capt PJ

[Lucky Louie]

A lot of the guys on the Cummins forum use the royal purple you mentioned. I put synthetic 80-140 in both of my diffs. when I changed the gear oil in them. My Dodge has the factory locker in the rear diff. instead of a clutch disk limited slip like the F-350. With the locker no need to add the friction modifier the limited slips need.......

[JETTYWOLF]

I just did mine. Used some west marine 90 weight. It looked like crap, but since it takes only minutes if you're able and quick I'm doing mine more often that once a year I think.

OHHHHHHHH. I thought we were talking outboards

[Deno]

I’m changing mine on Thursday also…

[pjay9]

Jetty...is the West stuff made for the new truck rear ends...as mine being limited slip needed to be somewhat special? Just curious! I would have put plain old 90 in my 79 Ford, but the newer Dodge...hummm! Capt PJ

[MacCTD]

Mobil 1 GL5 75/90, pretty sure 75/90 is the only weight recommended to run in the 3rd gen Dodge trucks with the AAM axles.

[21ftcc]

Don't forget to change the oil in the ....................

http://www.break.com/index/understandin ... lator.html

[welder]

21, That is TOTALLY AWESOME , I had no idea where that sound was coming from .
I have ordered the manual and test equipment , should be here next week.

Thanks for the heads up .

[Occams Razor]

Welder:

No bull.....Royal Purple is # 1 in that department hands down. After I redid my diff I broke it in for 50 miles with Mobil 1 and it ran hot as a SOB ! I drained it and put RP 85-140 and it only ran luke warm. That is a major difference !


Anothe no BULL **** story. I deal with Bobby Tasca ( the drag racer)on a regular basis in buisness. The family has a vintage race mustang drag car . After a freshen up for the season they ran a dyno test and then changed the engine oil, trans oil and diff oil with all RP products. Reran the dyno test and gained 15HP Bobby was shocked to ! It really makes a huge difference in friction reduction.

[welder]

RP it is then , now I just have to do it [ if it will ever quit raining ]

[Occams Razor]

Rain here to brother.....I cannot believe I was 140 miles offshore just a day or two ago ! Nasty weather.

[JETTYWOLF]

Jetty...is the West stuff made for the new truck rear ends...as mine being limited slip needed to be somewhat special? Just curious! I would have put plain old 90 in my 79 Ford, but the newer Dodge...hummm! Capt PJ

PJ.

works great in Honda's

Oh...we're still talkin' Dodges?

[21ftcc]

Saw this the other day

http://www.animegame.com/cars/Oil%20Tests.pdf

[Occams Razor]

I checked the results of that test and I am glad that it points people in the correct direction. A few things I must mention though.

1. Do not use RP in your new engine. It will glaze the living hell out of the cylinder walls and your engine will burn oil its entire life. I know first hand. Be sure you run your new engine on reg motor oil for the first 50 hours and don't be affraid to put some wood to it every once in awhile. Run it as you plan to use it ......These new engines use a keystone style compression rings that require very low cylinder pressure to seal them to the cylinder wall , but if the rings cannot seat to it , the rings will never seal properly. So best to use reg engine oil during initial break in. Honda does not rec sythetic at all for its outboards. Hmmmm I wonder why (damn things a so good if they use that **** they will never break). Break them in then switch out and you can run the living crap out em if you like to burn fuel.

Another note on this: If you spend alot of time idleing I do not rec RP . It will protect every other mechanical part in the engine but the rings will eventually glaze the cylinder walls. That is the only issue I find with RP. Its not the oils fault it the design of the engine itself. Knowing that don't be affraid to push your engine now and then it will prevent this from happening.

2. This is not the case in Differentials. As soon as you can take that liquid piss out of your lower unit and put in a high grade synthetic gear oil. Believe me you will notice a big difference ! The reg 90w after use alway comes out nasty no matter how often you change it . After two or three oil changes in the diff with RP you will swear the oil looks just like you put it in a drain time. It is simply amazing stuff. It is a must too....high ouput outboard put huge loads on those tiny lower unit gear sets and they don't take alot of BS to show problems if not treaded correctly. Don't forget your trucks diff is huge compared to your outboard lower unit ......now realize that your trucks diff is unloaded more than 50% of the time while in use but your lower unit in your outboard is fully loaded going up hill all the time. Its a wonder they last as long as they do !

Bottom line RP is some unbelievable stuff. Its pricy but the results speak for themselves.

[JETTYWOLF]

Finally something I can use!

Ya mean this stuff: http://www.royalpurple.com/gear-oil-m.html

Comence with Dodge talk, please.

[Occams Razor]

Hi all:

One other word of advice.....do not use RP in any clutched diff. It is to slippery for those apps. The clutches will slide and the lock up effect will not take place.

Auto trans also......if you are pulling or server loading your trans at regular intervals stay away from RP trans fluid. It is just too slipery for those apps.


Anything geared , metal to metal Go for it .

Dodge folks (mods)......leave the damn thing alone ! They got plenty of torque to do the job very well and you will only shorten the life of the engine buy making it produce full potential more often. Fine for the guys that go high performance all the time but for daily drivers you are better off to leave it alone. JMO

[JETTYWOLF]

O.C.

man you were right. I have a advanced auto parts right down the road (oh the subburbian city life...nice but also sucks big time too) so I stopped in and R.P. was 32 oz @ $19.99....called welder and asked him what he thought for the lower unit. Because right there next to it was Mobile One 75-90W and it was half the price.

-and my L-O-N-G-E-S-T run time is maybe in deep summer. 12 miles one way and back 12 miles. All to catch summer speckly bastards. aka: Trout.

don't know if I'm all that in need. only if I can go my usual 2 years with out a change.....

but at the same time I'm all about saving valuble petro and making more dinero, cause charter rates never change, but all my expenses go up.

[welder]

Did the rear end today with the help of Daddy'O [ Thanks Dude ] It took a couple hours because we painted the diff cover .

No leaks of drips yet.

Oh yeah, I got 4qt. of 75W140 GL5 here in town for $51.20 out the door.

[MacCTD]

Did the rear end today with the help of Daddy'O [ Thanks Dude ] It took a couple hours because we painted the diff cover .

No leaks of drips yet.

Oh yeah, I got 4qt. of 75W140 GL5 here in town for $51.20 out the door.

Was the the recommended weight? I thought is was 75/90 GL5. I put a PML cover on my 11.5", it adds another quart capacity and has a drain plug so you do not need to take the pan off every time.

[welder]

The 75W90 is the Minimum, 75W140 for towing and heavy loads.

Even the 140 is thin and flows easy

I'am LIKING that diff cover.

[Occams Razor]

Hello guys:

As far as oil weight goes (85-140) ect .The first number is the oil weight spec to flow at 0 degrees. So 85-140 flows like a 85 strait weight oil at 0 degrees. The second number is its protection rating . So 85-140 has a protection rating equivalent to a 140 weight oil.

You can use either the 75 or 85 in the diffs because pulling you do heat them up . The 75 will flow easier to your axle bearings though when cold.

As a rule the steeper your pulling gears the heavier the oil. So if you axle ratio is below 4.11 say 3.75 I would stick with the 75-140 . Steeper gearing I would go with the 85-140. My diff is a small 10 bolt GM but I have it maxed out with a 5.57 ratio. With a combined 1st gear in my trans (manual low) plus my diff ratio my gear reduction is 9 and change. That is alot of reduction ! But being such a small diff it can get HOT ! That pinoin gear is small compared to the big Dana and rockwell 3/4 ton and 1 ton diffs. So I use the 85-140 and it is perfect.

The RP gear lube is some super slimy stuff , its not just the synthetic oil its the additives they put in it also.

Again it makes a huge difference in the lower units of outboards. If any of you have ever seen what their innards look like you will relize that every little gain in lubracation will make a big difference !

[JETTYWOLF]

OH I HAVE SEEN INNARDS!!!!

Suzuki 140 lower units busted from corrosion back in the early 90's.
Between the bearing carrier and outside lower unit aluminum would build up salt......(sloppy azz fit and poorly engineered.)

So rebuilding was common place, till ya got so sick of them, like me, and eventually boxed the piece of crap up in a A/C condenser box and sold it all for $500 bucks in parts. Just to be rid of the the aluminum anchor!!

Yeah, lower units don't need any more stress or ways to break.

When I get "flush", I'll be going "RP" and trying it out. Even though I go no where and never run hard. But yes, I do alot of hours.....toodling.

My dad is all over it and may try it all in his BMW cycles. He's a Mobile One man now.
And a Iron-butt'er, so when he rides hard. It's from Fla. to California at 95 MPH.

[JETTYWOLF]

Hey O.C.

I slipped some Royal Purple into the lower unit today.

Now for that amount of $$, it'll clean my fish for me too, right??

Oh...it don't have to clean fish. But I'm hoping for at least 20 Nautical Miles per gallon now.

[welder]

Well it's been about a month with the royal purple in the rear end and so far so good , no noise or leaks.