75w90, 80w90 or 75w140?

[banzaj]

Hi guys. Complicated one here, need some help! What would be the best fit SAE grade and oil type (mineral/ synthetic) for the front and rear diffs and transfer for my 4wd v6 2006 4Runner? Here are the conditions:

1. Not looking for fuel economy here, but rather for the longest possible life expectancy of the diffs and transfer.

2.Locality. Climate: up to 100 F or even more in summer - for a month or so, and down to - 10 F in winter, sometimes even colder - but for no longer than 2-3 weeks in total, mostly within 5 to 14 F.
The car is driven in a city located in mountains, daily altitude difference en routes are from 0.5 to 1.5 miles above the sea level = severe conditions as per the manual and higher loads on the diffs and in general.

3. (As you are perfectly aware) The original manual quotes: for v6 models with multi-mode transmision, front and transfer - 75w90, rear - 90/ 80w / 80w90 depending on the temperature. For instance, v8 models with full time should have 80w90 all over. GL-5.

4. Well-known Toyota revision of 2008 pushes to switch to 75w85 all over. Fuel economy up, who cares about the diffs anymore?

5. Preference as to the SAE grade: gonna stick to the book. Good quality 80w90 may not be available though. If so, what about 75w90 all over? Or what about Castrol 75w140 in the rear and 75w90 for the rest? It potentially protects better due to being thicker, but wouldn't it be too thick and lead to excessive wear? For comparison: typical mineral 80w90's viscocity: 15 cct at 100 C and 150 cct at 40 C, pour point around -25 C. Synthetic Castrol 75w140 - 25 cct at 100 C and 175 cct at 40 C, pour point - 54 C.

6. Available reputable brands: no Amsoil/ Redline stuff here. OEM Toyota 75w90 / 80w90 / 75w85, all are virtually not available as I would have to order from a dealer and then wait for about two months - I don't possess that type patience and that type of loyalty to the dealer. So, the choices really are: Motul (imported from France), Liquimoly (imported from Germany), Mobil1 (made for local region, so not sure if the production standards and formulas are the same with the US/ European products) and Castrol (also local).

7. Would it hurt using the LSD compatible oils in this 4Runner with open diff? I know you should not do vice versa.

I really would appreciate your help. Thanks!

 

[aha2988]

I run Lucas 85-140 as recommended by all rock racers/ drag car drivers/ heavy duty trucks in my area. Its a very durable gear oil that doesn't break down durring high or low temps.

from what I've researched and discussed with many people is that synthetic tends to loose its viscosity durring high temps. some brands have even turned as thin as water durring high temp tests.

I def. recommend Lucas brand, as for the weight of the oil its not really going to effect much. you have open center differentials that don't require any friction modifiers so any of the weights you listed will be fine.

alot of members here seem to prefer Mobil1 75w-90 but i highly recommend a full non synthetic

 

[banzaj]

I run Lucas 85-140 as recommended by all rock racers/ drag car drivers/ heavy duty trucks in my area. Its a very durable gear oil that doesn't break down durring high or low temps.

from what I've researched and discussed with many people is that synthetic tends to loose its viscosity durring high temps. some brands have even turned as thin as water durring high temp tests.

I def. recommend Lucas brand, as for the weight of the oil its not really going to effect much. you have open center differentials that don't require any friction modifiers so any of the weights you listed will be fine.

alot of members here seem to prefer Mobil1 75w-90 but i highly recommend a full non synthetic

Thanks for the thought against synthetics. I also have read something on one of the Jeeps' forums re failure of some aftermarket rear diffs due to using synthetics ans subsequent higher temperatures of operation, but they were obusing them really hard off road I think.

As for 85w140 - do you have it all over? What's your total mileage on it? Nothing wrong with the parts? How cold is it in winter in your area? Its pour point is at about - 18 C/ 0 F and I guess it gets butterish long before this. It's cold here, so what would happen when this liquid is frozen, wouldn't it hurt even more then? It takes a while before it warms up after a cold night... several miles of driving on sort of a dry diff before the liquid melts?

P.S. Oh I see now, NC - relatively mild winters for you...

 

[Presta24]

I used mobile1 75w90 LS when I drained mine. It seemed to be the norm for the 4th gens on here. I also here a lot of guys use Lucas. Just wasn't in my price range.

 

[GMZ]

I've run synthetic 75W-90 in all 3 of my 4th gens without issue.

Curious why you don't want Redline or Amsoil? Their gear lubes specifically are superb.

However if an OTC brand is what you're after I'd go with Mobil 1 or Valvoline Synpower.

 

[luvmyt4r]

Personally I just put Royal Purple 75w90 in all my gear boxes over the weekend. EXPENSIVE, but I have used it is everything of mine. I have yet to hear anything bad about it.

 

[banzaj]

Curious why you don't want Redline or Amsoil? Their gear lubes specifically are superb.

Personally I just put Royal Purple 75w90 in all my gear boxes over the weekend. EXPENSIVE, but I have used it is everything of mine. I have yet to hear anything bad about it.

They don't sell fancy stuff in this country. To ship it here from the States will take about 3 months and 3 times a price. My limited choice is Mobil1 / Castrol / Motul/ Liquimoly.

I am interested in the opinions on how safe is a thicker grade, taking into considerations my complicated conditions - particularly wide yearly temperature range and excessive loads. The oil I've changed 20k miles ago is already dark grey in color in the rear, while it still looks new in the transfer and front (80w90 all over now) - I use 4wd like 4 months in a year.

 

[aha2988]

Thanks for the thought against synthetics. I also have read something on one of the Jeeps' forums re failure of some aftermarket rear diffs due to using synthetics ans subsequent higher temperatures of operation, but they were obusing them really hard off road I think.

As for 85w140 - do you have it all over? What's your total mileage on it? Nothing wrong with the parts? How cold is it in winter in your area? Its pour point is at about - 18 C/ 0 F and I guess it gets butterish long before this. It's cold here, so what would happen when this liquid is frozen, wouldn't it hurt even more then? It takes a while before it warms up after a cold night... several miles of driving on sort of a dry diff before the liquid melts?

P.S. Oh I see now, NC - relatively mild winters for you...

right, I deal more with high temperatures in my diff's causing issues rather than lack of heat.

it seems the 80w-90 has a pour point of -30(F) that may be your best option for dealing with the cold weathers. 75w-90 is just a little above -30(F). so either should be fine.

 

[aha2988]

They don't sell fancy stuff in this country. To ship it here from the States will take about 3 months and 3 times a price. My limited choice is Mobil1 / Castrol / Motul/ Liquimoly.

I am interested in the opinions on how safe is a thicker grade, taking into considerations my complicated conditions - particularly wide yearly temperature range and excessive loads. The oil I've changed 20k miles ago is already dark grey in color in the rear, while it still looks new in the transfer and front (80w90 all over now) - I use 4wd like 4 months in a year.

If you do any towing or have steep grades or see alot of highway speed mileage then you'll want to change your fluid every 15,000-20,000 you can push it to 30,000 but if you've price a third member lately you'll want to change it regularly. those are the conditions that cause the diff to heat up (where you would need a heavier weight gear oil) the transfer case and front dont see the load that the rear axle does so its not going to become discolored as fast. a thicker grade is safe its all about temperature requirements. as far as all the brands are concerned theres not much difference between them all they all use fancy language and rep there fluids. Lucas has been in the high performance scene for quite sometime It simiply handles the demands of abuse off-roaders and racers ask of there differentials.

again stay away from synthetic if you dont believe me call your local drive line shop and ask them what they have to say about synthetic fluid (they see the damage first hand in fact they like it because it brings them money but they'll quickly tell you to stay away from it.)

 

[GMZ]

They don't sell fancy stuff in this country. To ship it here from the States will take about 3 months and 3 times a price. My limited choice is Mobil1 / Castrol / Motul/ Liquimoly.

I am interested in the opinions on how safe is a thicker grade, taking into considerations my complicated conditions - particularly wide yearly temperature range and excessive loads. The oil I've changed 20k miles ago is already dark grey in color in the rear, while it still looks new in the transfer and front (80w90 all over now) - I use 4wd like 4 months in a year.

I saw your post over on BITOG, I was on my phone and didnt see that you werent in the states. All of those choices are fine, I would go with whatever is cheaper.

 

[JB.]

Banzai, I have no advice to give, but I thought OrdnanceMarine had some good stuff to say on this page.

http://www.toyota-4runner.org/maint...r-case-fluids-pics-included-6.html#post722317

 

[Koz]

This is a case where bigger is not better. The vehicle's components’ are engineered for a specific viscosity based on clearances’. If you use too high a viscosity, most of the lubricant will not be able to reach the surfaces effectively (especially synthetics). Do yourself a favor and use the recommended viscosity. There is no problem using a lower winter rated viscosity such as 75w-90 vs 80w-90 and is most likely better (lower pour rate).

BTW - If you use a high quality synthetic (such as AMSOIL - Severe Gear® Synthetic Extreme Pressure (EP) Gear Lube 75W-90 (SVG) ), you most likely will never have to change it again (it's good for 100K miles easily)!

Koz

 

[aha2988]

This is a case where bigger is not better. The vehicle's components’ are engineered for a specific viscosity based on clearances’. If you use too high a viscosity, most of the lubricant will not be able to reach the surfaces effectively (especially synthetics). Do yourself a favor and use the recommended viscosity. There is no problem using a lower winter rated viscosity such as 75w-90 vs 80w-90 and is most likely better (lower pour rate).

BTW - If you use a high quality synthetic (such as AMSOIL - Severe Gear® Synthetic Extreme Pressure (EP) Gear Lube 75W-90 (SVG) ), you most likely will never have to change it again (it's good for 100K miles easily)!

Koz

let me know how your ring and pinion hold up durring 100k miles of the same synthetic diff fluid...

 

[GMZ]

Do you change your oil every 3000 miles too?

 

[aha2988]

Do you change your oil every 3000 miles too?

every 4000, change all the case fluids every 15-20,000..

 

[aha2988]

this is what happens when you neglect your case fluids...

 

[G.I.G.]

Hmm, some interesting thoughts here on gear oil. I can only comment on my own personal experience and opinion. YMMV.

I changed my gear oil in all 3 diffs at 30k miles. The front and center diff fluid that I drained looked pretty good. The rear on the other hand was very dark and cloudy. I have the V8 with full-time 4x4 so I was somewhat surprised to see that the front diff's fluid looked as good as it did. I realize that even though it is full-time 4x4, that most of the power (and therefore the stress and wear) goes to the rear diff during normal driving conditions. Even though I feel that the center and front diff can go longer than 30k miles between changes, I go ahead and change all 3 if I'm going to take the time and hassle to change the gear oil in the rear. I have 80k miles on my 4R now with two gear oil changes behind me, and will continue to change the gear oil every 30k miles.

I went with the Mobil 1 75W-90 in all three diffs since my first gear oil change. I am not one to claim increased MPG's or performance by going to a synthetic oil, however, I did notice a big improvement when pulling in and out of tight parking spots with the Mobil 1. With full-time 4x4, I would notice slight binding up of the driveline when cranking the wheel on dry pavement. This is considered "normal" for full-time 4x4 cars and my old Grand Cherokee with Quadra-Trac did the same thing. Going to Mobil 1 pretty much eliminated that. Take it for what it's worth, but it tells me that the Mobil 1 was worth the few extra bucks per quart.

I don't tow often and rarely deal with extreme heat, so I don't feel the need for a high viscosity gear oil in my diffs. I do get a little more piece of mind with the lower 75W-90 rating (vs. 80W-90), spending a lot of time in the Colorado mountains when it is cold out. I have never heard until now that synthetic gear oil looses its viscosity at high temps. All things being equal (same SAE rating) I would still go with Synthetic. I'm sure Lucas is great stuff but comparing 85W-140 dino gear oil to 75W-90 syn gear oil isn't a fair comparison. Mobil 1 also makes a 75W-140 synthetic gear oil which I'm sure is good stuff as well.

Bottom line, if you're not extremely tough on your 4Runner, I don't think you can go wrong with most, quality gear oils as long as you change the oil when you should. There are many components on our 4Runners that are subject to failure and probably won't last as long as our diffs. Again, just my $0.02.

 

[Koz]

let me know how your ring and pinion hold up durring 100k miles of the same synthetic diff fluid...

I've run Severe Gear Oil in a supercharged PreRunner (W/locker) for over 100K miles (this truck is still running the oil to this day - well over 100K miles). These miles were VERY hard miles that included many trips to the track (drag racing) and towing at max rating! If you are not leaking or getting water in the rear, 100K miles should be fine. If you have any doubts have a UOA done at 25/50K miles.

BTW - dark oil doesn't mean the oil is bad, only a UOA will show the condition!

Koz

 

[GMZ]

this is what happens when you neglect your case fluids...

Ive been pretty open minded about automotive lubrication since joining BITOG but did you analyze the fluid? Or did you just blow your diff wheeling and blame it on the fluid?

 

[aha2988]

Ive been pretty open minded about automotive lubrication since joining BITOG but did you analyze the fluid? Or did you just blow your diff wheeling and blame it on the fluid?

water got in the diff through the outter seals over time and contaminated the gear oil, it blew while wheeling however when the first tooth snapped I wasn't even on an obstacle just a dirt road.

had I changed the fluid as I was should have I'm confident that ring an pinion would still be intact.

on a side note I could care less if y'all change your fluid regularly or not just wanted to let the OP know he had options other than 80w-90.