Gear oil efficiency military article

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Interesting read. Thank you for posting. Glad I'm using synthetic 75w-90 AXME Shell Spirax and Synthetic Valvoline in my work truck axles. need to squeeze out as much MPG as possible. .
 
Well... Its new for us, than mostly, all is better than dino 80W-90?
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"Guidelines" of my gearheads:
- Ditch 80W90 if you not in a country with lowest temps in winter around 60°F (Arabia/Africa regions). Use 75W-90.
- use 75w90 at stock cars
- use OEM 75w110 (or your own 60:40 mix of 75W-90 and 75W-140) if your car is tuned and has 75w90 OEM fill.
- use only 75W140, if your car manufacturer says, you must unexceptional use such oil or if you have Ubertuning (above Stage2)
- change MT and FT oils between 43.000 and 48.000 miles, if your car manufacturer speak about "lifetime fill"

Very simple recommendations
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But efficiency is not all about it. Wear protection is the other side, then repairs of all kinds of gears are ever expensive. For example, 70W or 75W in MT is FOR ME not the solution, if I can find 75W-80 GL-4(+) than works (I have).

Similar for FT or angle gears (AWD). 75W-90 with maybe littlebit lower Brookfield as another, is for me always better trade-off as manufacturers efficiency experiments with 75W85.
But commonly I self use standard 75W-90 for OEM stock cars without study and comparison Brookfield.
 
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Want to read this but the link is not downloading... "server not found". Did anyone manage to get a copy downloaded?

I have an '06 Toyota Land Cruiser. The PO took it to Jiffy and they changed the oil in the 3 differentials (good) but they used 80W-90 Mobillube HD Plus Gear Lube (dino). That's correct viscosity for the F&R diffs, but the center diff calls for 75W-90. Mobil describes this gear oil as "engineered for performance in heavy-duty commercial transmissions, axles, and final drives where extreme pressures and shock loading are expected".

That was is Southern California. I'm now in Southern Maine (economic refugee). It's cooling off up here and that 80W-90 is going to be too thick in the winter. Mobilube HD+ has a viscosity of 139 cSt @40ºC (V.I. 103) and a pour point of -27ºC. Mean minimum temperature here in January is -22ºC, not much above the pour point. Record low is -39ºC.

Don't like the idea of dealing with molasses gear oil on winter mornings, both from a lubrication perspective and because it will reduced the L.C.'s fuel economy even further.

Starting in 2008 (200 series) the Toyota spec is for 75W-85. But the differentials are not the same in the 100 series and are more similar to the previous 80 series (the center differential is almost identical). So I don't feel to solid about going with 75W-85.

Right now I'm planning on Amsoil Severe Gear 75W-90 in all 3 diffs. 102 cSt @40ºC, V.I. 166, pour point -43ºC (-45ºF).

What do you guys think?
 
Thank you for reposting the link in a more readable manner notempolimit. I have a much different vehicle-2000 Lexus LS 400 that suggests using 80w90 or 90 weight gear oil. I used Amsoil 75w90 for past 35000 miles and wanted to try different one-slightly thicker used quart of redline 75w110 and 11 ounces of Redline 75w90 for this change. The Amsoil looked very clean coming out. The current combination hasn't impacted driving or fuel economy thus far-haven't felt any extra drag or anything and fuel economy has been right around 20-21 similar to before. With your truck I might consider using 75w110 in rear-which would give you better cold flowing properties of 80w90 with better wear protection. Also found it interesting the Brookfield Viscosity of redline 75w110 was lower that the 75w90. I would use the 75w90 in front and middle differential. Thank you again for reposting the article.
 
Originally Posted by spiderbypass
Thank you for reposting the link in a more readable manner notempolimit.

It was google that found it... I put @spiderbypass description as the search term.

It seems from the article that 75W-90 oil is good for about a 0.5% increase in fuel economy. May not seem like much until you consider that you would get that 0.5% all the time for 50k miles or more for the cost of one oil change.

I'm all for blending oils to get the viscosity you want (as long as you're looking at the actual viscosity in the PDS and not the SAE number). But I don't see what I'd gain by using a heavier oil in the rear diff. The Land Cruiser 100 series has as conventional center differential which means both axles get the same torque (as long as no wheels are slipping). The rear diff has a larger oil capacity 3.5 quarts, so it may run cooler than the front diff which only has 1.7 quarts. I don't tow any heavy trailers and I no longer live in a hot area.

In the article they mentioned that 75W-140 gave better efficiency when high power at low speeds was called for.

I think the reasoning for the lighter oil in the center diff is that the transfer case is mounted directly to the automatic transmission which has an oil cooler. I just got my transmission temp working (Scan Gage II) and I've yet to see a ATF temp higher than 125ºF. The auto trans must be absorbing some of the heat from the transfer case keeping it cooler.
 
Originally Posted by NoTempoLimit
Want to read this but the link is not downloading... "server not found". Did anyone manage to get a copy downloaded?


I just downloaded the PDF in the first post - worked fine.
 
Detailed stuff. Thanks for posting.

I just bought 80W-90 conv. for my '05 Ranger. Should I return it for a 75W-90 synthetic?

There won't be much difference but any improvement is welcome.
 
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