rear oil

[jan bogert]

can you use 90 wt. oil in a model a rear? or is there a big difference in 600 wt

[pat in Santa Cruz]

there is a big difference from 90wt to 600w, which is about 250wt. If your seals are good, you can get away with 140wt in the differential, but not in the transmission as it allows the gears to spin too fast while shifting.

[Kevin in NJ]

What you need to understand is that the gears in the A are all straight cut and do not have a swiping motion like later gears. (well close enough to straight cut) These gears are best lubricated with a different type of oil then what newer cars need.

So you need and oil that is designed for high pressure situations. The correct modern replacements for that oil are like the Mobil 636 and such.

There are secondary issues that are not understood. The oil type of oils will also coat the internals. This keeps the un-vented axle housings from forming a layer of rust. Have you ever noticed that well run axles housings do not have any rust inside? They have this nice coating of oily greasy stuff that is a pain to remove. If you do not have the axles well coated then you risk rust flakes getting places you dont want them.

That is not to say the other oils do not work. Guys have been supposedly running odd oil concoctions for decades and claim they do not have problems.

STP anyone?

[V4F]

i use 80/140 with power punch !!!

[Terry, NJ]

Thanks for the explanation, Kevin. The 5 sp trans in my Saab 9000 uses 10-30 engine oil. I had a Ford 5 spd (Mazda) in a truck that used ATF. I realize that later Transmissions are under the EPA's MPG gun and the lighter the oil, the less resistance, ergo the less gas consumed. But I was always curious why this didn't apply to the older transmissions as well.
Terry

Originally Posted by Kevin in NJ

What you need to understand is that the gears in the A are all straight cut and do not have a swiping motion like later gears. (well close enough to straight cut) These gears are best lubricated with a different type of oil then what newer cars need.

So you need and oil that is designed for high pressure situations. The correct modern replacements for that oil are like the Mobil 636 and such.

There are secondary issues that are not understood. The oil type of oils will also coat the internals. This keeps the un-vented axle housings from forming a layer of rust. Have you ever noticed that well run axles housings do not have any rust inside? They have this nice coating of oily greasy stuff that is a pain to remove. If you do not have the axles well coated then you risk rust flakes getting places you dont want them.

That is not to say the other oils do not work. Guys have been supposedly running odd oil concoctions for decades and claim they do not have problems.

STP anyone?

[Louis]

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I've tried the "no lable" 600 and 1200 from the venders, all I got was a lot of foam and black drippings underneath , I use stright STP in the trans. and rear end, and have for the last two years, shift's great and no foam or leaks .
I'll never go back to what ever that black goo is from the vender's .
JMO.

[jan bogert]

it seems like 600wt. is just like 90 gear oil. anyway if i used 90wt. it would leak out? STEVE, what is that power stuff you are talking about? i'm just looking to do the rear not the trans. the trans is a t5. 5speed.

[Bruce Lancaster]

Ford used the Model A axle innards through most of 1932, and upgraded the spec to its first gear oil designed for the spiral gears...it was some odd number no longer around, like 220W (I'd have to find the owner's manual), and later retroactively changed the spec for all '32-48 to the later 140 and 90 versions. I'd say use 140.
If seals are bad, whatever you put in there will eventually get to your brakes, if good it will be fine.

[jan bogert]

thanks Bruce, i'm going to use the 140.

[hardtimes]

Originally Posted by jan bogert

thanks Bruce, i'm going to use the 140.

jan,
140..good choice, IMO! I've used 90w in a newly rebuilt model a rear end. For some reason, it got by the new seals and into new brakes..bummer!
I drained 90 and put in STRAIGHT 140...no more leaks ! Good luck in choosing.

[BRENT in 10-uh-C]

My experiences are like some of the others in that 85/140 is too thin. The rear end generally will not build enough head to turn the 85 weight into 140. STP really does not have much lubricating qualities as it really is just an oil "thickener". The steam lube such as the Mobilgear 636 is usually bottled and sold by the larger Model-A parts dealers as 600wt.

.

[Fred K-OR]

So what brand and what vendors does a person buy the "correct" 600 W oil or a current weight?

[George Miller]

If this helps I have been using 90 or some times 140w since my first model A in 1960. Never had a problem. My Sports coupe has 16000 miles with 90w with the old rear axle that was not rebuilt. I did put all new seals in.

[BILL WILLIAMSON]

Originally Posted by pat in Santa Cruz

there is a big difference from 90wt to 600w, which is about 250wt. If your seals are good, you can get away with 140wt in the differential, but not in the transmission as it allows the gears to spin too fast while shifting.

Are some in such a hurry to shift "QUICKLY," instead of pausing a moment to shift straight cut gears properly, that they resort to power wasting Gummy Goo oil to slow down the gears quicker?? Some concocted oils even FOAM!
The GHOST just informed me that foam is only for carpet cleaning & shaving. Bill W.

[Steam Engine Pete]

Brent,
I have always wondered about 600w oil. I am running 90 weight in my trans and my differential with no trouble. You mentioned Mobil 636 as a steam lube. I am not an oil expert but I would not use that as steam lube. I have been using Mobil 600w Super Cylinder oil for my steam engine and have often wondered if that is what I should be using in my T and my A for trans and diff lube since 600w is mentioned so often. Even though I am having no trouble I would be willing to switch as an experiment to see if anything works any differently.

Thanks,
Pete

[pat in Santa Cruz]

Originally Posted by BILL WILLIAMSON

Are some in such a hurry to shift "QUICKLY," instead of pausing a moment to shift straight cut gears properly, that they resort to power wasting Gummy Goo oil to slow down the gears quicker?? Some concocted oils even FOAM!
The GHOST just informed me that foam is only for carpet cleaning & shaving. Bill W.

not in a hurry to shift properly and never have been. But once the red light turns green, the guy behind me wants me to get it in gear. And that happens very slowly with thin oil.

[BILL WILLIAMSON]

Originally Posted by pat in Santa Cruz

not in a hurry to shift properly and never have been. But once the red light turns green, the guy behind me wants me to get it in gear. And that happens very slowly with thin oil.

Pat,
You 'posed to have it in gear 'afore the lite turns GREEN! Can't win NO drag races in neutral! NEUTRAL's only for neckin.' Bill W.