Synthetic in rear diff

[PKemp]

If you replace your gear oil with synthetic in the rear differential, what do you clean the oil out with first?

do you have to replace the seals?

do you have to use the additive?



???

 

[John - K5AWO]

Just use a hand suction pump (or remove cover and clean) to pull out the old fluid.



You don't have to clean out all traces of the old fluid, it mixes quite well and the percentage of old to new is very small.

 

[rrausch]

Keep an eye on your pinion seal after you switch to synthetics. Mine started to leak after I had switched. I switched back to non-syn and the leak stopped.

 

[Gary - K7GLD]

If you have a limited slip differential. some synthetics will render it inoperative, and no, you can't simply add friction modifier to restore proper operation in this case...

 

[PKemp]

How do you tell if its a limited slip?

 

[Gary - K7GLD]

IF it's a limited slip, and operating properly, if you jack up one rear wheel and then try to rotate it by hand it should be VERY difficult or impossible to do so...

 

[PKemp]

Got it, thanks... .

 

[AKAMAC]

My 01 has an option list on the glove box door..... Easier than jacking it up.

 

[Froadin]

I have heard lots of good results with people using Royal Purple. My only concern is it having too much friction modifier. Being only 2wd, I NEED the limited slip to be fully functional.

 

[Cooker]

The Royal Purple does not have too much FM. In fact I needed to add a little more to get rid of the chatter. LSD works great and is quiet with RP and a bottle of FM.

 

[Froadin]

Yeah, I haven't heard any complaints with the RP yet.

I will need to do this soon as the mileage is getting up there, and I will be hauling a larger RV pretty soon (not like I haven't been hauling medium to heavy the rest of the time).

I really like the synthetic for the temperature reduction abilities, and of course less friction is more efficient.

 

[TPlasek]

no complaints with RP here with my limited slip...

 

[Froadin]

Cooker, did you add the entire bottle of FM, or did you add a little at a time until the chatter went away?



TPlasek, did you have to use any FM?

 

[Ram4Sam]

Royal P.......

Froadin, I used RP 85-140 in mine and it works great right out of the bottle. I have put around 30,000 miles on since the install and the LS action is good. Sometimes I forget my truck is only a 2wd and get into spots I shouldn't be but haven't got stuck yet. While no two limited slip rearends are wound the same, RP works great in mine.



Sam

 

[Cooker]

Originally posted by Froadin

Cooker, did you add the entire bottle of FM, or did you add a little at a time until the chatter went away?

I tried 1/2 a bottle and that didn't seem to help much. The whole bottle fixed my problems. Every LSD reacts differently. You may not need to add any additional FM when switching to RP.

 

[Muleskinner]

MOBILE ONE

I used Mobile One in my 2001. 5 w/limited slip. I also put a small tube of FM from Auto Zone in. My limited slip unit works fine with no chatter. It will "Bark" the tires going around a corner if you accelerate while doing so,

 

[Sled Puller]

High quality synthetics will not cause a leak-rather, they will leak faster than regular oil, because they flow better.



Pumping it full of grease may stop a leak also, but it isn't whats best for the gear box.



Don't be too concerned with a little chatter, it just means they are nice and tight.

 

[Muleskinner]

Originally posted by Sled Puller

High quality synthetics will not cause a leak-rather, they will leak faster than regular oil, because they flow better.



Pumping it full of grease may stop a leak also, but it isn't whats best for the gear box.



Don't be too concerned with a little chatter, it just means they are nice and tight.

I agree. I have never seen synthetics cause a fluid leak in any vehicle I have put it in. And I have put it in a lot of vehicles. New and used.



Synthetic engine oil is the factory fill on a lot of high end and performance vehicles and THEY don't leak. I hear people say they experience leaks, but I have to believe they already had a seal problem and just did not know it.

 

[Motorhead]

I used the Royal Purple alone and my LSD works flawlessly!

 

[dpuckett]

Having had issues with limited slip not slipping enough and eating clutches in the past, I live by the credo "better to slip a little too much than not enough. " My personal opinion, of course. In the 93 D350 I had, I put Mobil 1 synthetic, with one tube of parts store FM, and had no problems; seemed to be the right combo for THAT pickup. Trying Valvoline 85-140 synthetic in Mom's in the AM, with 2 tubes FM; with regular oil, 2 tubes wasnt QUITE enough, IMO. Hopefully still have enough clutch material to let it get around corners. If not, I guess I know what I'm doing weekend after the 4th. (hafta wait for clutches to come in).



Daniel