Differential oil used

J

josh1331

Senior Member
I had a high speed gear installed..the mechanic refilled the differential with 90/80 oil instead of 600 wt oil as was originally in the reaR end.
Should I drain and refill with 600 wt? thanks /John
 
No immediate harm should come from the lighter oil but you might want to change to 600W before too long.

I like the 600W with 25% STP myself.

Richard
 
Dump it and put in the right stuff. I know someone who had this in the trans and rearend and lost the trans real quick.
The right oil is cheap compared to the price of new gears:mad:
 
You might note the STP is NOT a lubricant. It is a motor oil thickener usually added to old clunkers to stop them from burning as much oil. I think buying a lubricating oil of the correct viscosity(thickness) is a lot better than adding something that is NOT a lubricant to your differential.
 
STP is NOT a lubricant

mrtexas said:
You might note the STP is NOT a lubricant. It is a motor oil thickener usually added to old clunkers to stop them from burning as much oil. I think buying a lubricating oil of the correct viscosity(thickness) is a lot better than adding something that is NOT a lubricant to your differential.
Click to expand...

I agree wholeheartly with your statement but wait, the guy will come by here and tell us all the he has used straight STP for years with no harm.
 
I did my own research, looking on the Mobile site, found 600W, saw that it's uses are for steam cyls, and worm gear drives, then I found the 600 series of gear oils, they are listed for spur, and bevel gears, bI bouight a bucket of 636, it looks, feels and smells just like what I found in old untouched trans, and rears, and I have taken apart many bad engines that were full of STP, but I have never found it in good engines.

An old time used car guy told me his "secret" mix ---banana peels and sawdust!!
 
The used car guy secrets from 1966, to quiet the motor, Grits and STP, smooth shifts babys oatmeal or pablum, rearend grinding, butchers sawdust. And the warranty was enforced by Sinbad the one eyed dog with the tail bit off. Old cars were tough, relatively simple and had good steel gears, right for all kinds of abuse. My Mom bought an old Falcon had all of the above, she got even, Sinbad was a great dog.
 
One thing...the Model A gears, differential, and axles were kept 100% as is in the rear axle used on about 80 or 90% of 1932 B and V8 production. Ford altered only the housings, and did not go to the later rear until the very end of '32 production.
As of 1932, Ford had already switched to the early SAE family of gear oils, something like 220 weight from memory, and as the oils evolved 140 and 90 became the recommended lubes for all the '32-48 rears.
I think if your car had been serviced by a Ford dealer in the mid-thirties or later, it would have gotten 140.
 
Re: STP is NOT a lubricant

Mike V. Florida said:
I agree wholeheartly with your statement but wait, the guy will come by here and tell us all the he has used straight STP for years with no harm.
Click to expand...
not trying to start a urination contest, but it's hard to argue with Roger Kauffman's 100,000 miles in his 31 Wide Bed running pure STP in transmission and differential with no problems.......
 
Frank The Plumber said:
i would never knock the stp, just the grits, pablum and sawdust.
Click to expand...

Frank, I think grits taste nasty too!!;) Seems like a good use for them.



Back to Josh's original question, the biggest thing I think you will find between using 80/90 or 85/140 vs. 600 is the slight roar you will hear on the "coast-side" of the gear.

To calm your concerns though, let's think this through. You installed a newly manufactured ring & pinion manufactured with modern materials and methods which are suitable for use with the modern 80/90 lubes. Both the carrier & pinion bearings & races are modern-type units that also are ok using modern rear end lubes. The axle housing seals along with the driveline seal are all modern-type seals that are compatible with the R.E. lube your mechanic used. So the only real concern is if your mechanic trued-up the axle housing flanges where they connect to the differential (banjo) housing. A thinner oil/grease will seep through the gaskets and leak on your floor whereas the thicker lubes will not.

The final thing you can do to calm your concerns is to continuously drive the vehicle for 5 minutes on the road and pull over to a safe spot where you can make an inspection. Climb under the vehicle and place your hand on the axle housing tube and check the temperature. Next slide your hand over to the outside of the axle housing where the differential bearing races are and feel the temperature there. Do this on both sides of the carrier bearings and in the pinion bearing area. If there is no discernable difference between the temps, you know the bearings are satisfied with the lube.


.
 
What I would do is to leave the thing just as it is. If It does start to leak at the flanges where the gaskets are, go ahead and put in thicker stuff. 80-90 or 140 lube is actually a better lubricunt then 600W.

I would definately NOT use straight STP. It is not really a lubricant. It is for an engine that is about worn out so you can get a little more life out iof it.

I am a retired Mechanical Engineer that worked in the automotive industry for more then fifty years. I have also been working on these old fords for more then half a century.

Please understand, this is just my opinion.

Chris
 
I'm not an engineer! Not even a true "auto Mechanic"! However, I've been keeping my family"s cars on the road since 1961. I was always under the impression that STP was a good product. I recall when "Studebaker's Tinkled Pink" first came on the market it was hawked as a superior lube additive. Not a "Motor Honey" that took up wear. Yes, it did that too! But that isn't what it it was meant to do. I know what good "demos" are, yet STP ads showed someone picking up a screwdriver with the taper on it's blade with oil, but not being able to grip it tight enough to pick it up with STP! Conclusion! STP's a Superior lubricant. Actually, one of the best "wear taker uppers" was 10 weight vacuum pump oil. We used it in a Ford flathead V8 that was days away from replacement. We could no longer afford the Fox head or was it Wolf's head?
Regards, Terry
 
Chris, I think you're right about running 100% STP in the rear. I don't know why, but I wouldn't do it either. We had this discussion about Rear end/ transmission oils over in "Yesterday's Tractors" Ford N section. It seems that the ford N series tractors have to have GL1 oil, If not, the bronze bushings will corrode due to sulphur content. GL1 is hard to find. Like 600, you can't get it in the average AP store. GL 4 and 5 are much more common. Is there any bad effects from running say 75/140 or a comparable modern "mix"? I for the life of me, can't see any.
Regards, Terry
 
Terry said:
Chris, I think you're right about running 100% STP in the rear. I don't know why, but I wouldn't do it either. We had this discussion about Rear end/ transmission oils over in "Yesterday's Tractors" Ford N section. It seems that the ford N series tractors have to have GL1 oil, If not, the bronze bushings will corrode due to sulphur content. GL1 is hard to find. Like 600, you can't get it in the average AP store. GL 4 and 5 are much more common. Is there any bad effects from running say 75/140 or a comparable modern "mix"? I for the life of me, can't see any.
Regards, Terry
Click to expand...

Terry,

Actually if anything, the modern gear lubes are probibly overkill for the Model A rear end. The modern Lubes are designed to be used with Hypoid Gears which require more Extream Pressure additives to prevent scuffing and wear of the teeth. Model As as well as Banjo Rear ends used in Fords and Mercurys up thru 1948 all have Spiral Bevel Gears which do not require the same Extream Pressure Additives as the Hypoid Gears do. The additional Extream Pressure Additives will not harm anything.

Again, this is just my opinion.

I have no desire to get into a "Contest" about "you have to use a certain lub or your rear end will self distruct". I like to use scientific information and products that have been developed thru the years and for specific applications.

I am the one who uses the Modern very thin Manual Transmission Oil in the early Ford Transmissions (with with syncronized second and third) with very good success. This lubricant has been developed thru the years specifically for Brass Blocker Ring Transmissions. This techonology was not available when Henry first built the things. The only problem I have found is you have to have the transmission absolutely leak free of the stuff will run out on the floor. The thinner oil allows the blocker rings to contact the mating clutch surface on the gear much better and results in much better syncronization of the syncro sleeve and the gear. Much smoother shifts. Try it sometime, worst case, if you do not like it, take it out and replace with 600W or what you were using before.

Note, this stuff is NOT necesarially good for differentials.

Again, Just my opinion,

Chris
 
You must log in or register to reply here.
Back
Top