Hey everybody, I'm back.

Hoping you wonderful people can help me figure out lubrication!

Looking to replace all the oil in my 1974 144 (b20, m40 w/o OD) transmission, final drive, steering gear, distributor, and engine.

My list:
Engine - 15w40 Rotella Diesel (zinc is good for these old B20's?)

Transmission - Gear Oil SAE 80 (per green book & owner's manual)

Steering Gear - Hypoid Oil SAE 80 (per green book)

Final Drive - American Military Standard MIL-L-2105 B SAE 90(per green book)

Distributor - Fill oil cup with engine oil (per green book), lube contact surface of cam with "cam grease" (per green book), lubricate ignition advance mechanism with 2 or 3 drops on the wick of the shaft with 10w engine oil (per green book)

My questions:

Transmission - I've read that 80w90 gear oil is good. The bottles that I picked up are Pennzoil and have "limited slip capability" (need more additive when 3%< treat level is required) and are GL-5. This is *not* going to work for my transmission correct? It's too slippery? Can anyone recommend a brand? I'm in the USA, PNW to be precise.

Steering Gear - Can I use the same oil that I use in the transmission? Any SAE80 gear oil without additives? Or does it have to be a bottle that says specifically hypoid SAE80?

Final Drive - Is there an easy way to tell if I have a limited slip differential? It's listed in the owner's manual and green book as an option but without much information. What MIL-L-2105 B SAE 90 equivalent should I be looking for?

Distributor - Since I'm going with the heavy, zinc-y, diesel oil that's recommended by enthusiasts, what engine oil should I use for the oil cup? The same straight 10w oil that I'll be putting on the wick of the ignition advance mechanism's shaft?

Thanks in advance!

15W40 might be a touch on the heavy side if you live some place where it gets really cold (-20 C / 0 F range). Starting may be compromised. If you want improved cold weather starts and reduced cold start engine wear I would consider something like a 5W/40 or 5W50 synthetic. If you are stuck on using Rotella diesel oils they do offer synthetic versions for cold weather. As a side note, diesel oils may have more ZDDP than pure spark ignition oils; but, not significantly more, especially if the oil comes with dual C* / S* ratings. Most of the diesel oil 'design' is associated with dealing with the particulate crap that ends up in the oil as a result of burning diesel. If you really think you have a ZDDP issue you need to add purchase an additive - don't go over board.

LSDs were special order on the 140. I believe there is supposed to be a tag added under one of the bolts on the differential cover. Clean the gunk off the cover and have a look. Chances are that you do not have an LSD. You can also do the 'field check' method as described on Anthony Hydes's web page:

"jack the whole rear end of the car up so both rear wheels are just off the ground. Rotate a wheel by hand looking whilst looking at the other wheels rotation. If both wheels rotate in the same direction its an LSD, if they rotate opposite each other its standard."

The 2105-B oil is just for the LSD. For a normal diff use SAE 80 GL5. This will also work just fine in the steering box.

Limited slip gear oil has the wrong friction modifiers for use in a transmission. GL5 versions have sulphur additives which are bad for brass synchros (a separate problem from the friction modifiers). SAE 80 GL4 gear oil should be OK. Volvo's recommendations for the M40 have varied slightly over the years. Regular 30W motor oil is a safe and inexpensive option. If your synchros are getting tired, Red Line MTL has friction modifiers (the opposite kind of modifier that LSDs require) which can help. I use Red Line MTL 75W/80 GL4 in my M41. The only problem with Red Line MTL is that it has become stupidly expensive in the last 5 years. The list price is now more than 2x the price I paid 5 - 6 years ago.

Hey, thanks for the tips!

I ended up getting some 5W40 synthetic Castrol motor oil for the engine since she might be seeing some near-zero temperatures in the near future.

Picked up some regular 80W90 Valvoline gear oil for the diff and the steering gear.

I asked for some Redline, which they normally carry at my Advance Auto but they were out the other day so I'll be looking for GL-4 today.

Use the 90 diff oil in the steering box. Box is bound to be worn and the slightly thicker viscosity helps. Also if the box is leaking, common, it will help with that to to a small degree. It also means one less bottle on the shelf.
You can use the same 20/50 oil in the engine and overdrive gearbox. If the box leaks the OD will tell you it's low on oil by dropping out by itself. A small squeeze bottle of 3 in 1 is fine for the dizzy. Just keep the felt wet and add a drop to the side oiler now and then. No need to overthink this. Regular engine oil and filter changes should be done to the service guide.

I don't have OD unfortunately :/ but thanks for the info! I'll use the same GL-5 that I put in the diff in the steering gear.

MIL -2105B is an old designation that converts to GL5 gear oil. Is rated for hypoid gears, the diff and steering box.

Yes, these are flat tapped engines and require a certain level of Zinc and Phosphorous, both in the 1000-1300 ppm range. That’s why your hearing of the recommendation to use motor oils for Diesel engines, as modern oils for more recent oils have reduced amounts of these 2 components, as one or both of them will contaminate catalytic converters. Some modern diesel oils also have reduced level of Z&P.

Using. ZDDP additive is an alternative , however more isn’t better. Too much can lead to premature failure of the cam. I’ve never used it as I couldn’t figure out conclusively what the correct amount to add is.

I used this oil in my B20, not expensive and meets the requirements. My B20 isn’t used in freezing temps.

http://pqiadata.org/NAPA_15W40.html

I use the MTL in the M41 trans, and it has improved performance. I use synthetic GL 5 with no additive for limited slip etc, in the diff,

Thanks for weighing in! I'll be going with synthetic 5W40 oil for now and then when it starts to warm back up I'll see how she likes the diesel oil!

80W90 is fine for both gearbox without OD and diff, but use a GL-4 in the first and a GL-5 in the latter. GL-5 contains additives that can hurt some components in the gearbox, (e.g. the brass synchromesh rings IIRC).

Limited slip additives are only needed for limited slip differentials.
Non LS diffs send all the power to the wheel that has lost traction, so find a place where you can put one wheel on the snow/ice and one on a surface without. If you get stuck with the wheel in the snow spinning and the other one doing almost nothing, it's a normal diff.
Alternatively, if you chock up the rear of the car put it in first and engage the clutch, then both wheels will spin. Being very very careful and wearing sturdy gloves, slowly grip one of the spinning wheels and try to bring it to a halt. If this is easy to do, then it's a normal diff. All the power is now sent to the other wheel. A LS diff won't let you do this.

Thanks for explaining all that! I did a quick field test the other day and it's decidedly *not* a LSD. Plain old differential so I'll be using normal GL-5.

Hello,

I strongly suggest you don't test an LSD with the engine running as there is no need and it sounds dangerous.

To safely check for an LSD, jack up the rear of your car and with the engine off, the transmission in neutral and with the parking brake off, rotate 1 of the tires in either direction and observe the direction of rotation on the other tire. If both tires are turning in the same direction, you probably have a LSD. If the tires rotate in opposite directions you probably have an open rear end without a LSD. If you have a helper, you can test for a LSD by having both of you trying to turn the tires in opposite directions. If you can't easily make the tires rotate in opposite directions, you have a LSD or a locked differential.

FYI, there are LSDs that act like an open until a wheel lifts like the G80 that were optional equipment for some of the later rear wheel drive Volvos.

Here is what we would use for oils in your car. For colder climates, you can use a thinner engine nd transmission oil. But make sure whatever engine oil you use has enough ZDDP.

Engine: 30w
M40 transmission: Gl-1
Rear end oil: Gl-4/Gl-5(add friction modifier w/posi)
Steering box: Gl-1
Distributor fill cup(if equipped) & advance lube(felt under rotor): 20w

--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com