View Full Version : snythetic oil ?
10-13-2007, 06:33 PM
hi, i have a 2002 ranger edge with a 7.5 rear end with 4.56 gears and
a auburn limited slip installed on it i was going to change the gear oil
but i keep getting conflicting stories on what to use. i believe i was
told by a guy at auburn not to use a synthetic oil. and other knowledgeable
sources are saying you can. i use royal purple in my motor and i would
like to use a synthetic oil in the rear end as well. maybe amsoils new "severe
gear" oil. the shop i go to sold me some swepco 212 moly multi grade gear
lube to use but i am going to hold off and try to get some more feed back.
any help would be appreciated. thanks, joe
10-13-2007, 08:28 PM
Save your pennys, your rear end won't care if its got synthetic in it or not. Just run a friction modifier for the limited slip.
10-13-2007, 10:02 PM
go ahead and get the royal purple fluid. Get the heaviest weight for the back end tho.
10-14-2007, 12:09 AM
thank you for the feed back
10-14-2007, 10:17 AM
Maybe it would be a good idea to contact Auburn and see what they have to say about what goes in their differentials ? I had a post similar to this a week or two ago and the differences of opinion were quite pronounced. I researched this until the cows came home and I still don't have a definitive answer.
Short answer is unless you go way off the manufacturers specs, dino or synthetic wont hurt either way. The addition of a friction modifier seems to be linked with which oil you use. Some need the addition, others don't. To further add to the confusion, I spoke with a guy who builds rears for short track racing and he said all L/S need the modifier to make the clutches work properly. Others
indicate if there is no chatter, dont put it in as it may limit the ability of some L/S to grab as they should. He uses nothing but Mystic and asked me what I wanted when he installs mine ( factory L/S ) next Wednesday.
I said I'd let him know.....
10-14-2007, 01:50 PM
thank you for the info mr ngzcaz i know what you mean everyone i
talk to tells you something different i just want to put the right stuff
in there. i have talked with aurburn once before and that person said
not to use the synthetic put he did not sound to confindent, i sent
auburn a e-mail yesterday and i might call them agian tomarrow. i
see that you mention the word "chatter" which is one of the reasons
i wanted to pull my cover and inspect my rear end. i have had a bit
of a problem with chatter when i first start up my truck and go some
where. the first couple of times i let the clutch out i get some chatter
and some times it seems to shake the whole truck. my u joints look good
and about a year ago i had a centerforce clutch and plate, ect installed
and at the same time i had the auburn limited slip installed. everything
has worked ok untill the chatter started about 6 months ago. i have about
7-8 thousand miles on the set up. in talking with the shop that did the
work i do not think they used any kind of a friction additive. anyway any
advice is really appreciated thanks, joe ps. i also installed a camburg sub
frame about the same time the chatter started.
10-15-2007, 06:11 PM
FYI Since I too am installing a L/S this week, I started checking into different oils and their properties. As I was doing so I came across Auburns website. They recommend straight 80/90 oil with a FM. I wish I could as straight an answer from Ford. Other than universally saying add the FM no matter what, the choice of oils is wide open.
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