Running heavier weight gear oil? (5 Viewers)
- Thread starter Kernal
- Start date
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A little knowledge:
Unless you are running a SAE oil such as SAE 75 the viscosity of the oil does not change.
The "W" in the oil weight stands for "Winter" or rather the viscosity of the oil when it is cold.
Thus if you are running a 75W-140 it means that the oil viscosity when cold is 75 and will become a 140 when the oil warms up.
So running a oil with a larger operating range for protection will not have effect during the winter.
Because if its too cold for the oil to warm up then the viscosity will not change and remain the lower viscosity.
However, if it does warm up in the cold conditions the added benefit of the increased range in viscosity can be had.
This is why the oils with the wider range of viscosity cost more money.
SAE 75 vs
75W-90 vs
75W-140
All of them have identical viscosity when cold.
When hot things change dramatically.
The largest reason you would not want to run a oil with a higher viscosity is if the oil became too thick to effectively do its job.
So perhaps a 90 will flow properly though the oil journals where 140 is simply too thick.
Which mostly applicable to engines and not gears.
Unless you are running a SAE oil such as SAE 75 the viscosity of the oil does not change.
The "W" in the oil weight stands for "Winter" or rather the viscosity of the oil when it is cold.
Thus if you are running a 75W-140 it means that the oil viscosity when cold is 75 and will become a 140 when the oil warms up.
So running a oil with a larger operating range for protection will not have effect during the winter.
Because if its too cold for the oil to warm up then the viscosity will not change and remain the lower viscosity.
However, if it does warm up in the cold conditions the added benefit of the increased range in viscosity can be had.
This is why the oils with the wider range of viscosity cost more money.
SAE 75 vs
75W-90 vs
75W-140
All of them have identical viscosity when cold.
When hot things change dramatically.
The largest reason you would not want to run a oil with a higher viscosity is if the oil became too thick to effectively do its job.
So perhaps a 90 will flow properly though the oil journals where 140 is simply too thick.
Which mostly applicable to engines and not gears.
Land Speeder
InstaH8R
Who is putting a 90 or a 140 in their engines???
JEEBUS. I use 20W-50 for the inline 6’s and even then folks say I’m cray...
You could see better cold start protection from something like this Mobil 1 Mobil 1 Advanced Full Synthetic Motor Oil 15W-50, 5 qt. - Walmart.com
Land Speeder
InstaH8R
I live in South Alabama, my motors doesn’t know what cold-start is.
inkpot
SILVER Star
GEAR OIL is what the O P asked about, not motor oil. Typically in transfer cases, axle diffs. And manual transmissions, not engines.
- Thread starter
- #27
The original thread was started in 2011, however now that someone has resurrected it here's a short follow-up:
I tried a few different weights and eventually went with a ~50:50 mix of Royal Purple 75W-90 and 75W-140 along with 1-1/2 tubes of Lubro Moly 2019 Gear Treatment (molybdenum). I noticed the noise got less with heavier gear oil,
then less again once I added the Moly additive. and then as I put more miles on the vehicle the rear differential continued to quiet down.
Talking to a diff expert he said the ring and pinion teeth have likely worn in a new pattern which could be one reason it got quieter, along with the Moly additive. There is still a light roar/whine but I would say it's 75% less then what it was at it's peak 8 years ago. I have a complete spare rear locker sitting in a box but haven't seen the need to install it as long as things stay where they are. FWIW.
I tried a few different weights and eventually went with a ~50:50 mix of Royal Purple 75W-90 and 75W-140 along with 1-1/2 tubes of Lubro Moly 2019 Gear Treatment (molybdenum). I noticed the noise got less with heavier gear oil,
then less again once I added the Moly additive. and then as I put more miles on the vehicle the rear differential continued to quiet down.
Talking to a diff expert he said the ring and pinion teeth have likely worn in a new pattern which could be one reason it got quieter, along with the Moly additive. There is still a light roar/whine but I would say it's 75% less then what it was at it's peak 8 years ago. I have a complete spare rear locker sitting in a box but haven't seen the need to install it as long as things stay where they are. FWIW.
inkpot
SILVER Star
Actually, this is exactly what a bunch of us run year round here in the Phoenix area. Rarely if ever sees freezing, but we do get way over 111 degrees in the summer.
Land Speeder
InstaH8R
You quoted me, but we’re in the same page as to why the topic got switched to motors. I’m all about dif fluid.
On the topic of gear oil, I put in new output shaft seals on my 60 in the tcase and it still leaks. The leak is much slower but it does still leak a little. Is 75 90 full syn the right stuff for this tcase? Can I put something a little thicker in there?
