Rear diff oils?

[TomO]

I was courious about running synthetic oil in the posi rear diff of my 63'. Has any one ran into problems with synthetic oils and the posi packs? I am currently using mineral based limited slip 80/90 gear lube. I have decided to particpate in a 6 race points series at the track and I am looking to step up the protection of the diff components in my car.

TomO

[SS425HP]

GM used to have a special oil that was to be used in Posi-Traction rear ends. It was oil from sperm whales. Stunk to high heaven. Was awful. Don't know if it is still used or even available, today. Worked good, though. No chattering.

Fred

[bjburnout]

Hey TomO
Those posi's were never designed for that synthetic stuff.
I raced all kinds of posi rear ends and just used Castrol HYPOY C SAE 80W-90 and put in some GM Posi supplement (old part # 992694).
That supplement was like magic, never had a problem with the plates.......it even took out the clunk in some street drivers.

BJ

[Gus68]

Hey Guys!!! I my self see no reason why you couldn't use the synthetic in your older car. There have been many tests in different mags. and every time there was a slight horse power gain, not to mension the the better lubrication. As far as needing an additive, if you read most of the different manufacures labels the say they alreaddy have the additive for Posis in them. Actually if you are using your car for drag racing only you would want to run an oil WITH OUT any posi additive. The additive allows the clutch plats to slip easier around corners to prevent chatter and wear, but in a drag race only application you don't want any slip!!!
Just my opinion, I could be wrong.:)

[bjburnout]

Gus
The posi units I was referring to were on street cars........driven weekly, raced weekends.
If you use a posi unit for a drag only car it will soon become a doorstop.
Drag only use lockers, spools etc.....and your right - no supplements.
Tom if you go with the synthetic, you'll have to clean out the housing, axle tubes, bearings etc cause that stuff does not mix.
If your seals are not new and there is a slight groove from wear the synthetic will leak out everywhere......and of course there is the cost.
Our cars have run for years on the same hypoid that almost never gets changed and they seldom complain.
It was a Castrol Engineer that recommended the stuff in my other post and it worked fine........of course synthetic wasn't so prominent then and wasn't really considered because of cost.
He did say the synthetics were really designed for the new age stuff.

Just remember these magazines have become hugh advertising forums for products and I wouldn't doubt their paid for positive articles on new stuff.

BJ

[dq409]

Originally posted by bjburnout
.

Just remember these magazines have become hugh advertising forums for products and I wouldn't doubt their paid for positive articles on new stuff.

BJ

Even if they are not paid for the positive articles ,,,, can you imagine how fast the advertisers would drop the magizine if they trashed a products?
It`s too bad that the magazines are so dependent on them,,,,,, because then they could do real comparisons on product and pick a true winner in their tests !!

[bowtieollie]

Hi Tomo,

I highly recommend you run the syn oil in your rear.

I would recommend Mobil One primarily.

It will go a long way in reducing friction, the posi will function normally, and the gears/bearings will love you.:D

[Gerry]

Tom,


I recently overhauled the rear axle in my Suburban. It has a 12 bolt truck with a G.M. positraction. I used Richmond synthetic, 75W/140, with a GL-6 rating. No additional additive. I've put a couple hundred miles on it so far, no problems. Available thru Jeg's/Summit, etc.

[fatride]

I use synthetic Mobile 1 in all my rear ends posi and non posi. No problems at all. I use synthetic in my engine also and plan on using it in my 700R4 this summer.
:cheers

[TomO]

I thank everyone that chimed in on my question. I wanted everyones view point so that I could make a good decision. I think that I will make the change to synthetic oil, the rear end was rebuilt a year ago. I think now would be a good time to make the change.
TomO

[oil4kids]

I was holding off about putting my 2 cents in but here goes

Ive been using synthetic oil (Amsoil) since 1986. I started looking for synthetic oils after I went to flight school for the US NAVY. It seems that the military has been using mil spec synthetic lubes since the early 50's but kept it hush hush. It was the german scientists at IG Farbenindustrie that reinvented synthetic lubes during WWII . When the germans invaded the cold eastern front most of there petroleum lubes in the s-tanks turned to jelly and engines and gear boxes failed. The first PAO, a synthetic product using olefin polymerization, was manufactured. 1937 was also year that the Zurich Aviation Congress became interested in ester based lubricant technology. From 1938 to 1944 thousands of esters were evaluated in Germany with excellent results. In our own country ester basestocks were also being developed by the United States Naval Research Laboratory and introduced into military aviation applications during the 1940's.

When American GIs went into germany after WWII they were unaware that the german synthetic oil industry was producing vast quantities, and was uneffected by american bombing runs over petroleum fields. Just after the war we saw the first use of diesters by the British in turboprop engines for high temperature performance.

Anyway, petroleum is really made up of 1000's of different size hydrocarbon molecules, some lubricate and some dont. The idea behind a synthetic oil was to find which molecule lubricated the best and only synthesize that molecule. So the oil is uncontaminated by waxes and wrong size molecules found in conventional oils.


So today there are many synthetic oil sold , some are real and some are not and some are 100% and some are 10%. Its a big problem because there are few guide lines out there. AMZOIL (Amatuzio-oil) was created and became the first 100% synthetic diester based engine oil to pass the API sequence tests and receive API qualification in 1972. The Amsoil company was stared by a former US Air Force pilot.

The following year Mobil Oil began marketing the first PAO based engine oil overseas and in 1975 they began test marketing a synthetic PAO based synthetic in the U.S. called Mobil 1.

Today some of the best synthetics are Amsoil, Royal Purple, Redline, NEO (EON spelled backwards) and HPS. Im not sure HPS is available anymore, But it sure won a lot of desert racing in Baja. California. EON was Smokey Yunicks favorite at Indy in 1975.

If you use synthetic gear oil in old GM Muncie type transmissions ***USE GL-4*** rated synthetics-- the GL2-GL5 ratings are too slippery and you may have syncros that are lazy and dont engage correctly.

Also if you use a synthetic gear lube for the rear diff. with Positraction you may or may not need the anti slip additive package to losen up the clutches so they wont chatter around turns. Most posi addtives are made by Lubrizol.

Well my 2 cents are up.

[bjburnout]

Below is a summary I received from Castrol.....seems everyone recommends the new Synthetics....guess I'll just have to change my ways.......about oil that is.....and yes I will be using synthetic in my new Tremec.

"Castrol Syntec may be used in older, high mileage vehicles. Castrol
Syntec has been recommended for all US and foreign cars and has passed
industry tests for seal and gasket compatibility. However, while there
is no seal compatibility concern in older vehicles, deterioration of the
seals, resulting in an oil consumption problem, can arise.
Nevertheless, synthetic oil can be more fluid and if there has been
deterioration of the seals, a leak may become apparent.

We may recommend the use of GTX High Mileage in your engine. GTX High
Mileage is specially formulated with premium base oils and some
semi-synthetic components to provide the following benefits specifically
for high mileage engines. Compared to conventional motor oils, Castrol
GTX High Mileage:

- Is formulated with premium base oils to provide superior protection
against oil burn off.
- Contains seal conditioners that provide an added level of protection
and reduce oil leakage in high mileage engines.
- Contains proprietary additives that provide maximum protection against
engine wear and harmful deposits.
- Reduces deposit formation to minimize compression loss and maximize
engine performance.

GTX High Mileage does not breakdown as easily as other leading motor
oils, Thereby providing an added level of protection for higher mileage
vehicles."

Consumer Relations
Castrol North America
1-800-462-0835
castrol@idea-factor.com

[dq409]

I don`t know,,,,,, I get a little quezee when I here the words seal conditioners,,,,
Ever seen what a seal or rubber does when you let it soak in seal conditioner?
Swells and get all soft and gooey !

I wouldn`t use any of these oils in any engine of mine !!!!,,,, JMO,,,,dq

[bobs409]

Im with DQ. Call me old fashioned but I just don't trust modern things like this for my antique cars. Makers of this stuff will say anything to sell their products so remember, don't believe everything you read.

AC filters and regular 10w/30 Valvoline for mine. (notice, I said Valvoline? Yep, no more Pennzoil after our discussion on the board. Can't take the chance.)

[bjburnout]

DQ and Bob
Where were you guys when I was getting beat up over this?
My instincts tell to stay with what I've used for over 40 years and my cars are not complaining.
Plus I really hate the prices of those synthetics.
DQ, you're right about seal conditioners and Bob that quote from Castrol could be all propaganda...........
Thanx guys for restoring my faith.

BJ

[oil4kids]

At least in America we have a choice what oil to use. Im sure that in the old Iraq whatever oil they had you used or they shot you. That probably goes for the Kremlin too.

Those reading this post may be interested to know that Reeves Callaway switched to synthetics when he had turbo warranty problems then made it manditory for his twin turbo callaway corvettes and put a little metal emblem saying use only Mobil1. Then in 1992 GMC Typhoons and Syclone turbo SUVs made synthetics manditory for warranty and said it in the owners manual. Or at least it said it in my owners manual. The big turning point was when Chevrolet had trouble with premature wear of cams in the 32 Valve LT5 ZR1 Corvette, The LT5s were built by Mercury Marine in Oklahoma and assembled into the
ZR-1 vehicle at Bowling Green. Primarily a problem of high wear in colder climates the problem was solved by mandating the use of synthetics in 1993. The present day corvettes and mercedes still say to use synthetics to meet warranty.

[jim_ss409]

I just thought I'd add that virtually all heavy trucks now come from the factory with synthetic oil in the trannys, rearends and front hubs and the component manufacturers all offer longer warranty coverage and longer recomended change intervals with synthetic oil. There is also a substantial saving in the fuel economy as well. As for seals, leaking seals are not nearly as comon as they used to be. It's hard to say if it's the oil or if the seals are just getting better. Anyway, I think synthetic oils are here to stay and seem to work very well.

[bowtieollie]

premium base oils and some
semi-synthetic components

Don't waste your money on semi syn oils.

There is NO legal definition of "what is a semi syn oil"!

It can contain 1% it can contain less, it can contain more. The oil company marketing guys need to be shot for ripping off the consumer on this topic.

Castrol was sued over this. They prevailed in court ONLY because there is no legal definition for "semi".

So, you either use a full syn oil or you use a brand name non syn oil with an API classification of SL.

Save the money on the fake oil and spend it on the car in a better fashion. :cheers