Tips on Lubricating Your Jeep


The Universal Jeep CJ-3B Owner's Manual was a formidable document -- nearly a hundred pages, describing the function and maintenance of every major component of the vehicle.

1957 Owner's ManualIn those days it was quite possible for the typical owner to do much of the maintenance, troubleshooting and repair of their Jeep, and the manual provided most of the information they needed to do it.

Today, many CJ-3B owners know every nut and bolt on their Jeep, but the basic maintenance guidelines in the manual (which may no longer be with the Jeep -- no glove compartment, after all) can still be useful.

See the Lubrication Diagram and Chart (100K GIF), showing location, frequency, quantity, and type of lubricant required in fourteen main areas.

Taking account of developments in lubricants, and the periodic hard use that today's recreational Jeepers may put their vehicles through, here are some more recent recommendations on lubrication. -- Derek Redmond

See also a discussion about Lubricating the Steering Knuckles.

Recommended Drivetrain Lubricants

Greg: A Valvoline technical representative in the corporate office told me last week I should not use their gear oil in my 1954 3B differentials or transfer case because the phosphorous content in today's gear oil will corrode any brass or cooper parts in the differentials and transfer case.

T90 2-3 synchroWhat are the facts, not opinions, regarding the right kind of oil for the differentials and transfer cases that have brass and copper parts? And how many parts in an original differential and transfer case are brass or copper?

Oldtime: No brass, bronze nor any copper are inside of the differential housing. Both the transmission and the transfer case contain brass and bronze parts: 4 inside of the transmission and 3 inside of the transfer case. The gear lubricant migrates between the Borg Warner T90 transmission and the Dana model 18 transfer case. The fact is that certain EP additives can chemically effect the element copper and its alloys.

"Jeep" meaning Willys Overland / Willys Motors Inc. / Kaiser Jeep Corporation and American Motors Jeep Corporation are the final authority on their vehicles. Chrysler Jeep is much too far removed and seemingly uninterested. Therefore whatever lubricant "Jeep" recommends; that is the correct lubricant to be used.

The various Jeep service publications clearly specify certain lubricants for certain Jeep components and climatic conditions. That said not all service publications are in effect for all models of Jeep. One must know the relevant publications to fully know what is in effect for a particular model.

In other words, like the Jeep itself, the various service publications progressed (changed.) In fact Jeep specifically instructed its authorized service departments that most of the older service publications should be destroyed. This was because certain but not all publications were considered as outdated. Therfore many of those superceded publications are a rarity today, and certain valid data is now limited to only those with such references.

Allow me to begin with the earliest CJ publication and then I will indicate some of the changes made as the publications progressed.

The earliest CJ publication is called the Maintenance Manual Universal Jeep CJ-2A issued 1945. Here it states that the transmission is factory filled with mineral oil of the proper viscosity. The differentials are filled with hypoid lubricant SAE 90 EP.

* This manual is superceded.

The next notable change in print comes from the Mechanic's Manual Model CJ-3B Universal and Farm Jeep issued 1953. Here it states that SAE 80 or SAE 90 gear oil is to be used in the transmission. For the differentials it states to use hypoid lubricant SAE 90 EP for summer and hypoid lubricant SAE 80 EP for winter.

1953 Mechanic's ManualText quotes:

1) Gear lubricants containing extreme pressure ingredients such as lead, sulfur or chlorine compounds should not be used because of their tendency to corrode brass parts.

2) Hard shifting of gears in cold weather is a positive indication that the lubricant is too heavy a grade or the quality allows it to congeal at the prevailing temperature. If the oil is too heavy for easy shifting it will not properly lubricate the fitted parts.

3) Do not mix different types of hypoid lubricants.Use a light engine oil for flushing to clean out the housing.Do not use water, steam, kerosene or gasoline for flushing.

* This manual is superceded.

Service Manual 1002The next relative change occurs in the Universal Jeep Service Manual issued 1957. (SM1002 R1)Here the lubrication tables specifies Type GL-4 lubricant for both the transmission and the differentials. Use the same SAE weights as previously specified. In this manual the previously noted warnings regarding the use of transmission additive have now been omitted.

* This manual is superceded.

The next relative change occurs in the Universal Jeep Service Manual issued 1958. (SM1002 R2)

Text quotes:

1) A new multipurpose gear lubricant designated as API Service GL4 has improved load carrying capacity for most hypoid, spiral bevel and hypoid gear applications. GL4 is recommended in the lubrication specifications tables for transmissions, differentials (except PowrLok) and steering gears. The proper grade of GL should be selected to correspond with climatic conditions.

2) The Powr Lok differential requires a special lubricant and ordinary multipurpose gear lubricants must not be used. Use only Willys Powr Lok differential oil # 94551 furnished in pint cans.

* This manual is superceded.

The next relative change occurs in the Universal Jeep Service Manuall issued 1960. (SM1002 R3) Here the lubrication tables specify MIL-L-2105B for use in differentials.

Text quotes:

1) Use only flushing oil or light engine oil to clean out the differential housing.

2) Ordinary lubricants must not be used in the locking differential.Use only Jeep Powr Lok differential oil part # 94557 furnished in pints.Powr Lok may be cleaned only by dissasembling the unit and wiping with clean rags.Do not flush the Powr Lok unit.

* This manual is superceded.

1965 Service ManualThe next relative change occurs in the Universal Jeep Service Manual issued 1965. (SM1002 R5) This publication states exactly as was previously noted.

*This publication was never superceded for those who own model CJ-2A, CJ-3A or DJ-3A.

Service Manual 1046Last comes Service Manual Jeep Universal Series issued 1971, 73, 75, 77. (SM1046) Here the lubrication tables specify GL4 SAE 90 summer use and GL4 SAE 80 winter use. Use MIL-L-2105-B SAE 80 for the differentials.

*This publication was never superceded for those who own pre-1971 Jeep models CJ-3B, CJ-5, CJ-6, DJ-5, DJ-6.

Choice of Gear Oil

Mobil 1 75w-90

Oldtime: In my particular situation I have a meticulously rebuilt drivetrain and I expect high mileage service from it.I use Mobil 1 Synthetic Gear Lube 75W-90 in all 3 systems. I run Powr Lok's and this lubricant is very compatable. Also the use of one gear lubricant simplifies my inventory. Mobil 1 does not destroy the brass in a transmission but I do not recommend Mobil 1 for the transmission because the extra GL5 addatives do not allow the transmission synchronizers to shift smoothly.

I bought many quarts of it several years ago right before oil prices surged. Yes, it's relatively expensive but I do not change oil as frequently as indicated in the service manuals. I change these lubricants only when they show signs of contamination. Plus you can find it at local auto stores if you ever get away from your garage stockpile and really need some.

Amsoil 75w-90Amsoil MTF
If cost and availability are not a concern then I suggest Amsoil 75W-90 SEVERE GEAR Synthetic Gear Lubricant in the differentials.I would use Amsoil Synthetic Synchromesh Transmission Fluid in the transmission transfer case and also the Ross box.

Greg: If you were to replace the nonsynthetic oils I've put in my engine, transmission, transfer case, differentials, and Ross box with the synthetic oils you use, is flushing with light engine oil recommended by you for the engine, the transmission, the transfer case, the differentials and the Ross box when changing over to synthetic?

How light is "light engine oil" you would use, if flushing is recommended? What viscosity would you consider to be light, appropriate, and recommended if it were used as flushing oil? Or what type of product or process would you use to remove as much nonsynthetic oil, if flushing were recommended before changing over to synthetic oil

Oldtime: If you previously used an appropriate API lubricant of correct viscosity there is probly no advantage to change your gear lubricant to a synthetic lubricant. In fact converting to synthetic could become a problem. In certain instances synthetic oils or simply changing the oil brands can cause the aged seals to shrink. Shrunken seals = leaking fluids.

When flushing an engine, transmission etc., the whole conept is to remove more of the old contaminants. The thinner the viscosity of the flush the better it performs.

Tom: I have been using Sta Lube GL4 85W90 available at NAPA. The bottle rated this OK for manual transmissions with yellow parts. It specifically is labeled: "not corrosive to copper, bronze or other non-ferrous bearings and bushings" and "perfect for auto bus truck standard transmissions."

Lubricating Rear Wheel Bearings

Mobil 1 greaseJon Paulsen: If your baby likes to play in the water, a good synthetic grease will shed water better and be much less likely to become contaminated. I use Mobil 1 everywhere, except where I'm mixin' it with 90 weight, like in those beloved steering knuckles. There I'm using slick 50 grease, or other lithium based. Mobil 1 and lithium based are said to mix happily. Another benifit of Mobil 1 is the red color, which allows you to tell dirty grease from clean.

"If your rear axle has no grease zerks (newer axles): Woe is you. Every 12,000 miles, or after your baby goes for a good swim, or at whatever other reasonable interval the little voice in your noggin allows, pull the axle shafts, and clean and pack 'em by hand, while the bearings remain pressed on the shaft.

If you have grease zerks (earlier design): Recommended interval is the same as above, but since the process is much less labor intensive, I would do it soon after every swim and every time you're goosin' the other 20 some zerks on your baby with grease. Get out of your church clothes first, or the boss gets real mad.

Do the following the first time around, maybe skip it if you are confident the grease vents are venting. Otherwise you end up greasin' the brake shoes. God bless those stock 9 inch drums. They don't need any help with a good grease job. Get the back end up safely on stands and pull both drums so you can see the grease if it is going in there. It will come out behind the hub and drum.

Rear wheel bearing

Clean 40 years worth of crud off the vent hole. It's located on the top of the axle tube where it swells out on the end to house the bearing. It's about a 1/16 inch dia. hole. Do not push the crud down into the hole, or it could contaminate the bearing. Just scrape over the hole with a screwdriver. You might not be able to see the hole yet. If we're lucky, the grease gun will blast the hole clear.

There is also a larger, maybe 1/4 inch hole at the bottom of the flange at the end of the axle (the flange the brake backing plate bolts to). It should be scraped clear in the same manner. Judging by the drawings, it might be a little safer to dig around in this hole, but I'll wait until it has to come apart to clean mine up better. Its purpose appears to be to let grease out if the top vent fails. There is a boss on the "grease protector" connecting to it. The grease protector is outboard of the grease retainer. You can find a picture on page 336, fig Q-3 in the factory service manual form SM-1046, or page 483 in Chilton's Jeep CJ 1945-87. These are brake views, if you are trying to locate the drawing elsewhere. BTW, all of the gaskets and shims have an extra hole, which should be lined up with the boss and the hole in the flange, if you do a teardown.

OK, now begin pumping in the grease and watching where it comes out. Keep on pumping until it comes out clean. If it comes out behind the axle hub, you'll have to keep wiping it up so it doesn't fall onto the shoes. I had this happpen on one side, but it eventually came out the upper vent.

After it comes out clean, if it's co-operating and coming out the vent and not the seal behind the hub, you can put the drum and tire back on to make the next step only require two hands. Give the tire a big spin and pump in more grease, until it comes out clean or 4 or 5 more squirts. If it was still not venting, you'll have to turn the hub with one hand, wipe grease with the other, and run the grease gun with your feet, or enlist some cheap labor (THE BOY!) to pump grease. Don't trust the cheap labor to keep the grease off the brake shoes, as he's not old enough to understand the consequences.

Now that those upper vents are squeaky clean, a schmardt fella would do something to cover them up. I think I'll try a large stainless hose clamp with a rubber pad over the hole, loosening the clamp when going ape with the grease gun later.

My lower vent holes in the flange are still full of crud, but if I ever tear her down, and these vents appear to do what I think they do, I'll tap 'em for a plug or fitting to keep 'em clean.

Lubricating After Driving in Water

See Jon's 3B in the waterJon Paulsen: Being in water over the hubs means an inspection of all fluids after returning home. No need to fear as this is a good chance to spend quality time with your baby and bond with its unique underside.

After letting it sit overnight (it needs its beauty rest; also this lets the water settle), drain plugs should be pulled on the differentials, and gear boxes, then quickly replaced if good clean oil came out. Same goes for the steering knuckles, but just pull one of the bolts from the bottom bearing cap instead of a drain plug. This is followed by a finger in the fill hole to check the quality of the oil, then a squirt of 90 weight to top it off. If water went in, the fluids should be over full, too. If water or emulsified oil is discovered, it's best to drain, flush with kerosene and replace the oil. A field fix is just to let out the water, if it hasn't emulsified. If it is emulsified, it looks like a chocolate shake and functions as oil about as well.

I flush the diffs by squirting the kerosene with a squirt bottle and spinning the gears by hand, and the stock gaskets can be tossed in favor of silly-cone RTV. By the book, the hubs and wheel bearings should be disassembled and repacked. I just pull the cap on the hub and if there's no water there, and the knuckle is OK, I stop there.

Finally, all the grease zerks get at least a double shot with Mobil 1 grease, and maybe a triple shot if any water or emulsified grease comes out. Best to drop one end of each drive shaft and compress the slip joint to get all the water out if they were submerged.

Randy Buchanan suggests hosing the leaf springs down with WD-40 to keep them from rusting solid. He also says, "Don't get too much on the brakes if you can help it!"

Thanks to Jon Paulsen and the other contributors, and to Dan Fedorko who supplied the picture of the 1963 Manual. -- Derek

See also Lubricating the Steering Knuckles.

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Last updated 26 March 2017 by Derek Redmond redmond@cj3b.info
All content not credited and previously copyright, is copyright Derek Redmond