Gear oil as chainsaw bar lube?

I use bar oil, not because I think it is better for the bar, but because it seems to actually stay on the chain and not sling off onto everything else like my clothes, the ground or the saw. Gear oil will lubricate fine, but you'll ruin your clothes and boots and never get the smell out.
 
Bar oil is loaded with additives to make it tacky so it clings to the chain. If you could find a great deal on STP it would be a great replacement, maybe even too thick.
 
I've got so many leftover bottles of this and that oil on my shelf, it would be foolish for me to buy bar and chain oil. When I trimmed the low branches of my tree a few weeks ago, I poured some leftover Redline MTL into a bucket and periodically dunked the tip of the bar in it and spun the chain. Worked fine.
 
I've got so many leftover bottles of this and that oil on my shelf, it would be foolish for me to buy bar and chain oil. When I trimmed the low branches of my tree a few weeks ago, I poured some leftover Redline MTL into a bucket and periodically dunked the tip of the bar in it and spun the chain. Worked fine.
I have an older McCulloch saw with a dead oiler. I use one of those thumb pump gooseneck oil cans for it.
 
Sure you can use gear oil. You can also use pliers if you don’t have the right wrench. Maybe a hammer if you don’t have pliers.
Is gear oil a good lubricant for a chain saw?
No.
If you have nothing else, that is to say there is no bar and chain oil available and you must use the chain saw, any oil is better than no oil. But you will experience higher wear on your chain and bar. Oils are formulated for their purpose and a chainsaw is very different from an engine or transmission or differential. Lubricants are designed to prevent wear, to cool and to prevent rust and oxidization. The most important requirement is viscosity, which changes with temperature. The proper viscosity for saw chain oil at ambient temperature above 15 C / 60 F would be a ISO 150 or a ISO 220 if really hot ambient temps exist such as fighting forest fires (when you really need your chainsaw to last). ISO is the viscosity grade designation for oils other than motor and gear lubricants. ISO 150 is very roughly comparable to straight SAE40 motor oil and straight SAE90 gear oil. (Motor oil grades and gear oil grades are not the same). Motor vehicle multi-grade oils have the wrong viscosity at cold temperatures, the 75W of 75W-90 (The “W” stands for Winter). 75W is in the range of SAE 20 motor oil. The second number of multi grades (ex: the “90” of 75W-90) represents viscosity at operating temps of 100 C / 212 F which your saw chain probably won’t see while it’s still sharp using the wrong oil (which won’t be long). A straight SAE90 gear oil would however be in the right-ish viscosity range for ambient temperatures above 15 C / 60 F to use on saw chain.
The next most important quality for the lubricant is to cool the sawchain. Then prevent rust which usually requires a tiny amount of additive. So in order to achieve these requirements the lubricant has to stay where it is needed. There is no sump or containment as with an engine, transmission or differential. No grease seals as with bearings. What is done is an additive is formulated into the bar and chain oil to make it extremely tacky so it will stick to the chain instead of being flung off at high speed. Did I mention bar and chain oil is tacky? It’s really really really sticky….so your saw chain and bar have sufficient lubricant to not wear out prematurely.
Proper high viscosity and really really sticky are the defining characteristics of bar and chain oil. No gear oil, transmission oil, motor oil, vegetable oil, waste oil etc has these characteristics.
Just buy the bar and chain oil and don’t try to save money by using whatever you have leftover. You won’t save any money at all after you replace prematurely worn saw chains and bars.

I need to get to some long-postponed chainsaw work. It seems that I'm nearly out of bar lube oil. While I was in a hardware store today, I passed on some store brand bar oil at $10 a qt. The brand name lubes were far more money. Although I have a couple of vehicles that use it, I somehow have far more auto gear oil than I will ever use. Everything from 75w90, 80w90 to 75w140.

Would auto gear oil be a passable substitute for chainsaw bar lube? I believe most bar oils are rated 30 weight but I've heard that the engine and gear oil weight ratings are not directly comparable. Perhaps cut it a bit with some ATF that I have no use for? I'm guessing that it will fling off more than the correct lube. Or should I just break out of my cheapskate suit and buy Supertech for $7 a qt.?
 
For decades I have used the oil that I drain out of my automotive engines when changing the oil. I have also used transmission oil, gear oil, anything that was removed from the cars during a lube change. 'Never seemed to make any difference in the longevity of my chain or bar. It's a chain saw for sake. It gets into the dirt and muck. Maybe a thin oil helps the crud get thrown off the chain better, less particles to cause wear?

All my saws got a lot of use after this hurricane IAN a month ago. Dealing with 10 trees down, big ones, still working on it. 'One thing slowing me down is my Tennis (chain saw) elbow that resulted from my old age limitations.

ali
 
For decades I have used the oil that I drain out of my automotive engines when changing the oil. I have also used transmission oil, gear oil, anything that was removed from the cars during a lube change. 'Never seemed to make any difference in the longevity of my chain or bar. It's a chain saw for sake. It gets into the dirt and muck. Maybe a thin oil helps the crud get thrown off the chain better, less particles to cause wear?

All my saws got a lot of use after this hurricane IAN a month ago. Dealing with 10 trees down, big ones, still working on it. 'One thing slowing me down is my Tennis (chain saw) elbow that resulted from my old age limitations.

ali
You want oil that clings to the chain to keep the links lubricated, not something that flings off easily.
 
$10 a quart for store brand? Ouch. Our farm store had it for $8 a gallon.

Try Amazon or a parts store. You definitely want to use the correct stuff.
 
You can buy chainsaw bar & chain oil for what like $15 / gallon at most hardware stores. Why not use the real thing? Pretty much any oil will do the job but is likely to make a bigger mess flinging all over the place.

The stuff I use is pretty heavy, seems to be somewhere between a 40 weight motor oil a 90 weight gear oil.
"Why not use the real thing?" Maybe because all the trees are down and all the bar oil is sold out, not available.
 
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