Okay, so did a bunch of searching and reading on here and found that 75w-90 was the recommended diff oil and 5w-20 is the recommended manual trans oil. However, while unsuccessfully searching my 04's owner's manual for wheel bolt torque (found it on here at 81 ft-lbs), I found the recommendations of 75W-140 and ATF+4.

So, did MB and Ma Mopar change their minds in later years, or what? Can't find much else.

Already changed diff oil with Mobil 1 75W-90, but thinking about changing it again with Royal Purple 75w-140. Found one thread that mentioned it helped quiet the whine. I have a very light ring/whine only at very light throttle above 50 mph.

However, planning on changing trans oil next weekend. Already have some ATF+4 that I use in my 727. So, not sure on the trans. Pretty sure on the diff...

 

As far as lubrication purposes, I think any of them would work just fine. But if the statement about Royal Purple is true, then give it a try.

James

 

I used Amsoil 75W-90 in the diff, and tossing Amsoil 5W-20 in the manual tranby here shortly. Not sure about the 75W-140 though...or why you would use ATF in a manual.

 

Well, it's not the first time I've heard of ATF in a manual. It's been used for years in place of power steering fluid. I just recently quit using it in my '67 PS, because it gets a little confusing when you have a trans leak AND PS leak.


I think I'll just go get some Royal Purple 75W-140 for the diff, and will think of the 75W-90 as a flush. If it helps with the whine, it's worth the money. I never hear it with the windows down, but it won't be long till I have to start rolling them up. I think I will probably also go with Royal Purple 5W-20 for the trans. I don't have any shifting problems, but just hate to go over 100k miles without changing it.


Just out of curiosity, what do your manuals list for fluids?

 

The manual transmission came from the factory with ATF. (I believe my 96 Viper came with ATF as well). The excellent Crossfire technician that work on my car in 08 drained the ATF and replaced it with synthetic motor oil.
I had purchased a couple different transmission "additives" to give him before he changed it, and he told me, "I'll put them in if you want me to, but nothing is more slippery than synthetic motor oil, and you will probably just be wasting your money". I figured he knew a lot more about it than I did so I just went with the motor oil.

 

Did anything change?

 

I really didn't notice any difference. But my car is an 04, and they're notorious for their "notchy" 1st. to 2nd. gear shift. It's just something you get use to, and seems to get better after it warms up.
I figure synthetic oil is about the best lubricant money can buy (I 've been using it in my cars religiously since 1979) so that's going to stay in my tranny.