Limited slip diff

[westyss]

I had almost forgotten about this until I read about the warranty thread which jogged my memory.

After my trip I decided to have all my oils changed in the tranny, diffs, etc, after the service we took off for another small trip and started to notice the rear diff making some odd noises and eventually started to click/hop about while turning corners, especially tight turns, seemed like the diff was packing it in!

It was pretty obvious right away to me that during the service they used the wrong oil which was the case here. After a call to my dealer about what they used in the diff I was told it was some standard diff oil and not the proper oil specific for the diff as stated in the owners manual? The service manager there said that sometimes regular diff oil can be used and will have no effect or if it does effect it then use the proper oil??

Of course I felt like that was BS but thought it might warrant a discussion to get to the truth.

So............ any info on this? Are these diff needing the proper limited slip diff oil or can one use some other? Seems to me like a mistake by a mechanic who has not had the proper training and they are covering up.

Also, what kind of damage can this produce?

 

[DiploStrat]

A classic, clutch based limited slip differential almost always requires a special oil. Use regular gear oil and you will get clunks and all manner of noise and, eventually damage. Don't have a Mitsubishi but I did have an Isuzu and it clunked like mad when the dealer got it wrong.

Your dealer should correct at no cost to you as the wrong oil will probably void the warranty.

 

[westyss]

The dealer corrected it promptly at no cost, but I am not convinced that a limited slip diff can use regular diff oil, has anyone heard of that? Is that common?

 

[DiploStrat]

An Eaton locking differential and, perhaps, some other, non clutch limited slips use normal oil. All of the clutch based systems that I have heard of require a special oil. Used to contain whale oil which made it very expensive.

Others may have more precise information.

 

[whatcharterboat]

Used to contain whale oil which made it very expensive..

Hi Fred......amazing bit of trivia right there. I did not know that.

Yes. Must use Lim Slip oil in the rear diff. As above, LSD diff oil has an additive that allows the clutch packs to slip. If the correct oil is used and the diff still clicks annoyingly on tight turns, usually caused by the clutches sticking, extra additive can be used. As an example, GMH Limited Differential Lubrication Additive can be used in Isuzu rear LSDs with great success. BTW Isuzu have their own additive too but have seen the results with the GMH product.

If anyone has this problem, the oil should be drained, then the additive mixed in with the oil externally ( don't know why it wouldn't mix by itself in the diff but the instructions are specific) and then when the diff is refilled , the oil needs to be bed in......to do that requires running the truck in tight figure 8's for 20 minutes to allow the oil to move through the clutches in the diff.

Thought this worthy of posting as we have had to help a couple of customers out with this problem recently.

 

[westyss]

Thanks John and Diplostat, this fits with what I thought initially and really points to the dealer not being aware enough of the particulars of these trucks, I know they send certain mechanics for training but I think I ended up getting a newbie that did not know or put the effort into researching it.

Sorta fits with the over tightening of the wheel lug nuts, just dont trust anyone, even a dealer! I plan on doing my own services from now on as in a few months my five year warranty is done, its a weird thing how that worked out, the truck was built in 2006, so they ended up having to warranty it for almost 10 years!



Now if I found out the diffs used whale oil the tree hugger in me would have bought a different truck:sombrero:

 

[westyss]

Last thing, what component would be the likeliest to be get damaged with continuous use with the wrong oil? Has anyone heard of such an event and what was the result?
Seems to me like the additive is something one should be dragging along on trips just in case.

 

[Gatsma]

The friction plates will be the victim of wrong(or non-additive) oil; basically you would end up with an open (or "standard") diff.

 

[westyss]

The friction plates will be the victim of wrong(or non-additive) oil; basically you would end up with an open (or "standard") diff.

Eventually I guess, but seems to me like something might give before those wear enough to not grab, bearing, something?

 

[pugslyyy]

Eventually I guess, but seems to me like something might give before those wear enough to not grab, bearing, something?

I think the most pronounced effect is increased tire wear.