Hey Guys quick question.

This weekend I thought about changing my rear differential fluid and replace it with Mobil 1 or Royal Purple Synthetic.

My question is this. I found a guide that recommends purchasing a pump in order to pump the fluid out if someone wants to do this on their own.

Do you guys recommend I take this to a shop or would it be something that could be easily done bymyself. Im pretty new to auto mechanics but i have worked on a my car a bit..most of the time its just oil changes but just thought I would ask.

Thanks

On a difficulty scale of 1-10 it's about a 1.5

You can get a pump at your local auto parts store.

You also need two bottles of GM LSD additive which you can get from your local GM dealer.

http://www.c4guru.com/articles/ChangingDifferentialFluid.pdf


You can use what they call a suction gun to do this which is about $10.00 retail.

any good differential brands you guys recommend?

I have 3.73 gears so im looking for something good

:tongue:

Get the pump and also a little extra tubing to get it down into the bottom of the diff for sucking it out.

I just use some plain old Valvoline 75w90 gear oil. Don't forget to add your limited slip additive first!

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You want to go higher or lower?

Every shop I've talked to says richmonds are noisy, and recommended Superior or Precision, (and of course you can't go wrong with OEM dana/Viper/GM gears)

Many if not all of the new ring/pinions are made in China or elsewhere overseas. The cheaper ones definitely are.

I have Richmond Gears..Havent really heard any weird noises or anything and from what I could tell they have performed just fine. Even if they are making noise I cant hear it...my exhaust is loud but never had a problem...

I dont know what gear oil was put in but i thought about putting in Royal Purple or Mobil 1...

My case was weeping a bit to begin with but when I put Mobil1 in there it seemed to wash away the factory RTV. What was left of it literally fell off the case when I seperated it.

With my new gears I dimpled the aluminum mating surfaces, used The Right Stuff, and stuck to dino oil, it's been leak free since.

Your mileage may vary.

I use Castrol synthetic 80w140 Limited slip axle lubricant with NO additive. Dont add anything to the synthetic oils at all unless it says to on the bottle, its allready added into the fluid and adding more wont help.

If youre using Royal Purple in anything, dont expect it to last as long.

yea, I have always used the two bottles of additive (per Gordon Killebrew) and then topped of with conventional gear oil.

There are no bad things to contaminiate the oil back there - think coolant or fuel. So the lifespan isn't all that short.

out of curiosity

why wouldn't synthetic gear oils last as long as conventional ones?

technically im not too worried about changing it out. I love these little projects...

I change my oil in about a month or two because I ride my car really hard and try to have fun.

I just want to get the most out of my gears you know? I have 3.73 back there so basically i want something that will best protect my gears. But then again if you experts recommend conventional oil with GM LSP then ill do it. Just wanted to hear thoughts about Mobil 1 or Royal Purple

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Who told you they dont?
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NO!!! I use and recomend CASTROL SYNTHETIC!!!

My opinion on Royal Purple is pretty simple, ive heard and seen too many bad things happen that seem to have only happened since this rubish went in. Not so much in diffs, but in engines, most notable was a Subaru Legacy, engine was always well serviced and owned by a mate of mine since brand new, somewhere around 135,000 to 140,000 (thats abit over 80,000 miles) he went from Castrol Synthetic (used since he first changed the oil) over to Royal Purple of the correct viscosity, and while the car ran fine for about another 5,000klms, by then it was starting to show signs of a failing engine with serious wear, and it didnt make it to 150,000klms. I felt that engine shouldve certainly gone on alot further than that, cause these typically dont fail that early in the piece even with abit of flogging.

Engine all torn down reveilved what i believe to have been "excessive wear caused by lack of sufficient lubrication", and this was through no fault of the owner, lack of attention to oil level, lack of oil flow, lack of oil pressure (which wasnt much by the end) nor due to incorrect oil viscosity. The mechanic he used firmly believed it was caused by the Royal Purple lubricant, and stated to us he had seen simular premature wear before where Royal Purple had been used.

If you read on their website they had a section that shows the "effects" of Royal Purple as i call them, something that sounds quite good in theory by using some sort of ultra fine abrasive compound in the oil (only way this could occur too) to "machine" the internal sufaces, while the engine is in operation, to a mirror smooth as silk finish. In doing this, it is effectively wearing away at the friction surface of the parts, which is something you want to avoid at all costs, cause the oil is there to prevent this, not accelerate it.

Stick with Mobil 1 or Castrol for synthetics mate, although Valvoline make some great fluids and lubricants too