I know this subject has been gone over many times here and other sites as well. I have spent much time researching this subject and my conclusion is that you must use a gear oil free of EP additives that are found in most every gear oil on the market today. What is needed is a GL-1 Mineral Gear Oil. I found two that are this and not synthetic either (which may be another issue so stay clear) Here is what I have found that is OK for the early transmission with synchromesh: Napa Mineral Gear Oil 90w And what I am using is Millers Mineral Gear Oil 140w Available from: Performance Racing Oils Inc 227 Sherway Rd Knoxville, TN 37922-2218 | (865) 200-4264 ask for Karl Poelti! Tell him Mark from Connecticut sent you! Great Service!
Thanks, I have been trying to figure this out also. Are you using corn head grease in the clam shell ?
Yes I am and also in the steering box. How about you? The rear in the Coleman car is about ready to go back in. Think we found the issues with the noise. Driveshaft was not shortened properly (it was crooked). was wiping out gears etc.. Anyway Happy New Year!
I know what you're supposed to use. What happens if you run just normal everyday gear oil? Before I fixed a leak I ended up topping up with modern gear oil since it ran out the torque tube so fast.
HAPPY NEW YEAR TO YOU ASWELL. I had been using Royal Purple Max gear. Leaks like a sieve. I have all fluids drained now and going to try the millers. I was also using a multi purpose grease in the clam shell. I think it was to light and turning to oil, so I'm going to change that also. did you use the cork gasket or rubber rope seal. Thanks
Just drain it good and go with what I suggested. I know lots of guys that use GL-4 & GL-5 rated oil and have not have problems so I think it would take some time. You never know. I did myself and also seen some brass in oil. Anyway that is why I spent the last month researching it. That and there was nothing else to do in the F%#$in Cold. My two 32's are drained and ready for the Millers!
i was told the "newer" type oils are too "slippery" for the blocker rings so they don't get the next gear spinning/synchronized right away and cause a grind. i had this problem recently with a '42 jeep 3 speed. changed the fluid and it shifted good [well good for one of those crappy, clunky pieces of shit ]
So are these oils best for all old transmissions? I've got a '55 F-100 with an original four speed still bolted up behind the Y-block. It doesn't shift as nicely as I'd like it to, and I think it might be the oil that is in it. It seems pretty thin. On that same note, should I also drain and refill my rear end as well? You know, just to be on the safe side. I am just not sure what oil is in there.
I would think they are. Changing the oil is never a bad idea especially if you do not know when it was last done.
Check your owners manual, the Ford spec is probably 50 wt oil, at least in some transmissions if you want to try that. I've been running 90wt gear oil in both the differential and three speed box for almost 20 years now. If it eats brass synchros in the transmission, it must take a while.
Let me take a crack at this.... For a 1939 Ford transmission, as has already been pointed out, GL-1 spec gear oil in SAE viscosity grade 90 is what should be used for the vast majority of cars/trucks, though you might consider SAE 140 for summer use in extreme high temps. If you use SAE 140 and you have a hard time shifting the gears, back it down to SAE 90. The difference between GL-1 and GL-4 is the amount of EP (extreme pressure) additives used in the oil, with GL-4 having more of these additives, and GL-5 having even more. EP additives (sulfur-phosphorus compounds) can be aggressive toward yellow metals, and the hotter it gets the more aggressive the oil gets. GL-5 gear oils were really designed for use in hypoid differentials, because of the heavy sliding action of that type of gear set, not really intended for synchro transmissions. Though many (most?) of the major lube companies now blend their gear oils with non-aggressive EP compounds, so as some guys have reported here, they've used them with no issues. Still, it is best to just avoid them, as they aren't necessary. Here is an explanation of the different GL-_ gear oil specs: http://www.oilspecifications.org/api_gos.php So, back to GL-1 oils, what to buy? Here are several that are available out there: http://www.chevronlubricants.com/en_US/products/products/chevron-gear-oil-gl-1.html#.WK9wwW8rKUk http://www.tractorsupply.com/tsc/pr...eral-90-transmission-fluid-2-gal?cm_vc=-10005 https://www.amazon.com/Warren-Oil-GL90-1-GEAR-OIL/dp/B00HFLH3ZW https://www.smittysinc.net/images/products/files/128_Super_S_GL_1_Gear_Oil.pdf http://www.trusouthoil.com/premier-gl1-lubricants/ https://phillips66lubricants.com/product/transmission-oil-sae-90 http://www.docs.citgo.com/msds_pi/C10011.pdf Chevron and Tractor Supply are 2 great sources, there is a Chevron distributor in just about any metropolitan area, just google search for the distributor in your area. Tractor Supply, they'r everywhere. Or just order thru Amazon.
Ancient 600W has nothing to do with modern oil grades. If it was on the modern scale, it would not be a liquid. 600W is steam cylinder oil. It is roughly equivalent to modern 140W.
The 600W I have bought is a hell of a lot thicker then 140. I usually have to heat it a little to get it to pour
The 600wt I get for my Model A runs like the Old STP additive we used to get in the 60's like Chris says. It don't pour, it rolls out of the bottle. The Wizzard
Thickness is not always an indicator of lubrication properties. Maple syrup is about SAE30, but I do not suggest running it in a crankcase.
I've just changed my oil from 80/90 to 140, mainly due to the standard factory oil leak at the back of the box. I used penrite mineral 140, which is an Aussie brand. It's stemmed the leak and have to say it's improved the shift, bearing in mind it's just come out of summer here and still hot. See how it shifts in the cold. Sent from my iPhone using The H.A.M.B. mobile app
Anyone want to send me a sample of the 600W oil so I can have it analyzed and we'll know just what's in it and what the actual viscosity is. As I recall from digging up information in the past, as Gimpy posted the chemical make up of the oil is basically the same as Steam Cylinder Oil, or what is also known as Compounded Gear Oil, or rather gear oil with natural or synthetic animal fats that provide some additional lubricity. The viscosity grade as I recall was about like an ISO 460 or 680 grade.
BTW, I'm not sure what the W signifies in the name, as there is no such thing as 600W viscosity. The W that you see used in multi viscosity grade oils, like 10W-30, stands for Winter, not weight. Let me repeat that, the W stands for WINTER, not WEIGHT. WEIGHT is not a technical term used for viscosity grades, it is something people hafve picked up and repeated, but no sanctioning body uses that term.
I've been running gl-1 90 weight from napa for the last year and half in my model A pickup with 39 trans. No problems. About my only complaint is when it is super cold out the shifter is a little stiff when starting put in the morning. But it resolves itself pretty quickly. Sent from my SM-G900T using The H.A.M.B. mobile app
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