I recently read that 75W-90 gear oil is actually equal to 10W-40 motor oil in viscocity. I like the AW and EP additives that gear oil has in it, which is why I use it as a lube for my guns. But what I'm wondering, is there something about gear oil, particularly 75W-140 full synthetic, that would be bad for my engine? I would use maybe 1/2 quart at most, mixed with something like 5W-20 Pennzoil yellow.
Gear oil in a crankcase a bad idea?
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MolaKule
Staff member
There's more to lubricant applications than viscosity.
Start with this link:
https://bobistheoilguy.com/forums/threads/additives-xii-multifunctional-additives.41173/
Gear oils and PCMO's contains different additives for different reasons.
In a nutshell, gear oils contain additives that would be very harmful to an engine.
Purchase a good PCMO and stay away from gear oils.
And choose a firearms lubricant that doesn't contain additives that could harm them as well.
Start with this link:
https://bobistheoilguy.com/forums/threads/additives-xii-multifunctional-additives.41173/
Gear oils and PCMO's contains different additives for different reasons.
In a nutshell, gear oils contain additives that would be very harmful to an engine.
Purchase a good PCMO and stay away from gear oils.
And choose a firearms lubricant that doesn't contain additives that could harm them as well.
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Mola is indeed correct.
Truth is, you don't mix applications in this case: keep the engine oil in your engine and gear oil in your gearbox, that's it!
don't be adventurous.
Q.
Truth is, you don't mix applications in this case: keep the engine oil in your engine and gear oil in your gearbox, that's it!
don't be adventurous.
Q.
Just out of curiosity ( thread drift ) what might be some additives in GL which would be a problem in firearms ?
Originally Posted By: CITYSLICKER
Just out of curiosity ( thread drift ) what might be some additives in GL which would be a problem in firearms ?
I'd like to know this as well since I've never found a lube that works better than 75W-140 synthetic gear oil.
Just out of curiosity ( thread drift ) what might be some additives in GL which would be a problem in firearms ?
I'd like to know this as well since I've never found a lube that works better than 75W-140 synthetic gear oil.
dnewton3
Staff member
FANTASY
Wouldn't it be lovely if life were just that simple. One oil for all known uses.
REALITY
Different oil desinations and classifications exist for a very good reason.
Don't mix them.
Wouldn't it be lovely if life were just that simple. One oil for all known uses.
REALITY
Different oil desinations and classifications exist for a very good reason.
Don't mix them.
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Mola is spot on. The additives in a gear oil are very dissimilar to those you need in an engine oil. Completely different operating environments.
Although I will say many years ago I once had to run straight weight 70 in a completely shot Ford 400 V-8 that was worn to bits. Burned anything else by the case. That's about as close to a gear oil as I've ever placed in an engine.
Although I will say many years ago I once had to run straight weight 70 in a completely shot Ford 400 V-8 that was worn to bits. Burned anything else by the case. That's about as close to a gear oil as I've ever placed in an engine.
Kestas
Staff member
For starters I'm pretty sure a Grade 5 gear oil has sulfur-based EP additives that would seriously harm copper-based journal bearings in the engine.
I always figured gear oil would work REALLY well for a short time as the EP films would reduce friction, until those EP films started to break down and corrode everything...
I think gear oil should be ok for guns, but it's probably short on corrosion protection since it's designed for a closed environment.
I think gear oil should be ok for guns, but it's probably short on corrosion protection since it's designed for a closed environment.
Gear is corrsive and acid based not exactly the thing you want to expose ordinence steel to. The PH is completly wrong for engines and firearms.Some stills like the steel Remington use's for it's barrels can react to acids in a very bad way with micro cracking on the surface. You wouldnot be able to see this damage witht he naked eye but it would definately cause accelerated wear from gas's and and powder abrasion. You also do not want any thing with solvents or acids getting to the the rust blueing wich is basicly controlled corrision caused by hot salt bath. Now on a crome lined bore and chamber of a sub machine gun or such I would use strong oleic acid to clean it out since the crome lineing is not going to react.Acid and ammonia need to be used cautiously and one when needed on ordence steel because depending on the batch it can react differently tot he solvents. It might be fine 100 times in a row then the 101st time you use it you could end up with deep pits and micro cracking in a rifle that was up to that point a great take driver. When you look at how little is needed and how seldom you need to clean a rifle stuff like butch's bore shine are cheap and go a long way and will remove the copper safely.Even synthetic motor oil can cause some issues even though I too have never experinced them. I would no more use gear lube on a gun then I would brake fluid! Thngs like Sweet's and Shooters Choice and Barnes Copper cleaner can be used when needed but not on a regular basis. I am partial to BreakFree CLP because I grew up with it thanks to Uncle Sam and have found it works great if you are not a knuckle head and do not baste your rifle in the stuff like a Thanksgiveing day Turkey with butter. All the people I know that have had issues with BreakFree over used the stuff wich like any lube over applied is going to attract dirt and dust and lint and carbon residue etc..... The area most prone to problems is the recoil/main buffer drive spring. People will over all it and it gets alll nasty inside the tube with sand and before you no it you get a jam. The other problem is people not keeping their champer and gas rings clean.If the chamber is clean and the gas rings are in decent shape and you do not over oil the M16 it has decent reliability. If someone over oils it and does not keep the gas rings and chamber in decent shape it is all over jam city!!!! Handguns need just a toch of grease onthe slide and a few drops of oil and they will usully run all day and all night.
Bolt action guns ned even less oil. People do themselfs in with oil!
Bolt action guns ned even less oil. People do themselfs in with oil!
What is the difference between gear steel and gun steel?
i think you would be crazy to add gear oil to car engine..and it sounds like jb knows his stuff about what to use on guns...call me gullible, but i trust the mfrs. to know what oils should go on a gun and in a car...these chemical engineers know a lot more about oil than the avg person does
See, now we're getting somewhere. I've never been able to get straight answers as to why certain things shouldn't be used outside of their normal job.
Don't confuse voluminousness for knowledge.
MolaKule
Staff member
This is off-topic, but go to the Firearms Topic and search for what makes a good firearms lube; I posted a comment there some time ago.
As Kesta and others have stated, the high levels of phosphorus and sulfur would most likely eat the bearings in an engine due to their corrosive effects.
Again, that's why we have different lubricants for different applications.
As Kesta and others have stated, the high levels of phosphorus and sulfur would most likely eat the bearings in an engine due to their corrosive effects.
Again, that's why we have different lubricants for different applications.
MolaKule
Staff member
As far as steel materials, both firearms and differential components may use 4140 chromoly steels. Most axles would be made of heat treated 4140 or 4130, but other differential components would use other steel alloys.
Another difference would be the type of heat treating in different steel alloy components.
Let the Internet be your classroom:
http://en.wikipedia.org/wiki/Low_alloy_steel
Another difference would be the type of heat treating in different steel alloy components.
Let the Internet be your classroom:
http://en.wikipedia.org/wiki/Low_alloy_steel
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Ha, ha. In the early '80s my co workers and I bought a '70 Camaro to carpool with. It was shot when we bought it ($300) and we got 100k miles out of it before it finally gave out.
The engine didn't even have an air filter when we bought it!!!It had an inline 6, 3 speed stick and nothing else!
In the last 25k miles of it's life it really started consuming oil. Smoke was the order of the day!
We elected to run straight 75w-90 in the engine and it worked for a while - but then we were back to that ever present cloud that followed us everywhere.
At one point we put regular 'ol car oil back in it to stop the horrible smell of the burning hypoid and my God! it as if an atomic bomb had gone off!!!
We tore the engine down in hopes of shoring the old girl up but she was too far gone.
We wound up just throwing the car away. In it's final state of tune it had an MSD ignition system and anti-foulers on every plug. After the neighbors realized that the car was finally gone, they brought me a bottle of champagne.
So I agree with MolaKule on this - never use hypoid in an engine (unless you have to).
The engine didn't even have an air filter when we bought it!!!It had an inline 6, 3 speed stick and nothing else!
In the last 25k miles of it's life it really started consuming oil. Smoke was the order of the day!
We elected to run straight 75w-90 in the engine and it worked for a while - but then we were back to that ever present cloud that followed us everywhere.
At one point we put regular 'ol car oil back in it to stop the horrible smell of the burning hypoid and my God! it as if an atomic bomb had gone off!!!
We tore the engine down in hopes of shoring the old girl up but she was too far gone.
We wound up just throwing the car away. In it's final state of tune it had an MSD ignition system and anti-foulers on every plug. After the neighbors realized that the car was finally gone, they brought me a bottle of champagne.
So I agree with MolaKule on this - never use hypoid in an engine (unless you have to).
Originally Posted By: Tempest
Don't confuse voluminousness for knowledge.
He actually was rather concise and clear, as is Molakule. It's just a complicated topic, although the results are simple enough: engine oils go in engines, gear oils go in gears, and gun oils go in guns.
Don't confuse voluminousness for knowledge.
He actually was rather concise and clear, as is Molakule. It's just a complicated topic, although the results are simple enough: engine oils go in engines, gear oils go in gears, and gun oils go in guns.
Would this semisynthetic corrode the engine(crank bearings)?
MoS2 Leichtlauf 10 W-40
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
or this MoS2 additive?
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
They both contain molybdenum disulfide. I use the additive with a synthetic.
MoS2 Leichtlauf 10 W-40
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
or this MoS2 additive?
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
They both contain molybdenum disulfide. I use the additive with a synthetic.
Originally Posted By: SonyAD
Would this semisynthetic corrode the engine(crank bearings)?
MoS2 Leichtlauf 10 W-40
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
or this MoS2 additive?
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
They both contain molybdenum disulfide. I use the additive with a synthetic.
If my understanding is still correct, MoS2 in proper suspension form shall stay good in motor oil (and that's why some motor oils come with added MoS2 in them).
Q.
Would this semisynthetic corrode the engine(crank bearings)?
MoS2 Leichtlauf 10 W-40
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
or this MoS2 additive?
http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/e_1092.html
They both contain molybdenum disulfide. I use the additive with a synthetic.
If my understanding is still correct, MoS2 in proper suspension form shall stay good in motor oil (and that's why some motor oils come with added MoS2 in them).
Q.
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