Low viscosity and/or synthetic gear oil?
 

Has anybody tried using low viscosity or synthetic gear oil in their transmissions and differentials...which should theoretically reduce drivetrain friction? I know that using synthetic engine oil is known to improve mileage...just wondering if anybody has seen the same results by improving the lubrication in their drivetrains?

And if you go that far, you might as well use synthetic grease in CV/U joints and wheel bearings.

Heres an article I found after a few minutes surfing google:

http://www.machinerylubrication.com/...?articleid=167

I use synthetic gear oil in my Matrix. However, the previous owner put it in. I'm going to be switching out to synthetic on my Paseo too as soon as its warm enough to do some work on it again. However, its more of a longevity thing IMO. I'm sure there is a slight effeciency increase, but I'd be willing to bet that the increase is so small you'd never know. I work in the power transmission industry (not an engineer, but I work with them) and we don't use synthetic to increase effeciency. We do use synthetic to increase life of our gearboxes and the load bearing capabilities of them.

Synthetics will outperform non-synthetics at low temperatures while the machinery is warming up to normal operating temperature. So there would be an efficiency improvement during that time vs. regular mineral oils that don't have the same stability. Though, I'm with Daox and would say the improvement (comparing the same weight oil) would be hard to detect.

You'll also note that none of the major auto lubricant makers claims efficiency improvements in their marketing by going to synthetics (of the same weight).

My opinion is that synth is worth pursuing (for a fractional efficiency gain) if you live in a cold climate, or if you normally only do very short trips.

You're more likely to get an improvement in efficiency by switching to the lowest viscosity lubricant that you can safely use in your application. See: Effect of gear oil viscosity on transmission efficiency (Metro owners take note)

Wow! I went to that link and using the AC Delco lubricant actually resulted in huge gains in drivetrain efficiency...on the order of 25%-35%. :thumbup:Considering that, I would consider looking at gear oil viscosity to be pretty important.

I recently read a magazine article where they tested regular oil against synthetic, and they showed rather large improvements. of course they were testing for max horsepower, but with no other changes they basically showed a change in internal engnie resistances, or internal drag. I would think that anything thats reduces system drag should affect performance, at least to some extent.

I have no empirical data, [yet] but putting thinner grease in my rear wheel bearings,feels like there is less drag now than before.
Could just be that the seat of my pants got lighter though.
Once i get the engine back to peak, I'll run over and get some extra bearings and run some a,b,a,b, tests.
maybe test with power unit out? hmmmm the wheels are turnin.
definitely easier to pull up & down the street. Hmmmmmmm.
More "crazy old man stuff again"

Where do I find one of those pull scales? Hmmmmm.

I sure am glad my wife LOVEs me.
S.

I began my mileage hobby back around 1980, during the "energy crisis", when I was fortunate enough to get my hands on a 4-cyl Pinto :D. It seemed like everything I did got me about a 2% gain: header & glass pack, water vapor, leaning the carb, new-fangled radial tires, etc. But when I put Amsoil synthetic in the engine, trannie and differential, I saw a 16% increase. Of couse, I don't see those gains now. With fwd, sealed CV joints, automatics, and manual tannies using ATF, only the engine remains to be syntheticized. (I love making up words)

I've also used synthetic grease on wheel bearings, and had a booger of a time getting them torqued correctly. I believe the reduced friction was leaving the bearings running cooler; hence they did not expand as much. I've heard similar stories from others using synthetic grease on bearings.

And when logging, I used synthetic engine oil on my chain. Though much thinner and less "clingy" than bar oil, the other guys were astonished at the lack of wear on my bar and chain. I'm sold on the friction reducing properties of synthetics. This is all anecdotal, but that's my opinion, and that's all I've got to say about Thayat.

and for the truly frugal among us, synthetic's extended performance life almost makes up for the extra cost on initial purchase.