Gear oils, diff and t-case

XJsavage

CounterCulture
Joined
Aug 15, 2009
Location
Lyle's Ford SC
As I search I'm finding a lot of info on what oil is best to run in mainly stock application, but little that gives the brand vs breakdown temperature ratio.
I found out recently that TSC traveller brand gear oil has a very low life expectancy, and worse yet, breakdown temp when used in automotive drivetrains that endure what a daily driven vehicle would see that's been built with off-road use in mind.
In my exact application, everything except my engine uses gear oil. I don't know exactly what my late 70s NP435 and 205 could possibly get up to temperature wise. I'm to the understanding that a rear differential can climb to 200 degrees easily especially during break-in. What concerns me is I've heard that cheap off brand gear oils (TSC traveller) breakdown is at 120-ish and happens to be what I put in my rear diff. Rumor has it that name brand gear oils obtainable at parts stores withstand 180(?)
Any clarification is greatly appreciated.
 
I have run lucas in everything since ecgs recommended it to me years ago. My dodge has seen some rough miles with too much weight behind it and is holding up well.0827191701_HDR.jpg
 
I have run lucas in everything since ecgs recommended it to me years ago. My dodge has seen some rough miles with too much weight behind it and is holding up well.View attachment 337541
Do they carry it in 5 gallon bucket size? I guess that's more of a question for my parts store guy. Since both axles, trans and T-case call for roughly the same weight, that should take care of everything.
 
Do they carry it in 5 gallon bucket size? I guess that's more of a question for my parts store guy. Since both axles, trans and T-case call for roughly the same weight, that should take care of everything.
Not sure but I know I had to order it for my dump truck because all the local stores combined didn't have the 70 quarts I needed to service it. Lol
 
Do they carry it in 5 gallon bucket size? I guess that's more of a question for my parts store guy. Since both axles, trans and T-case call for roughly the same weight, that should take care of everything.
Yes, cheaper by the gallon off amazon though.
 
As I search I'm finding a lot of info on what oil is best to run in mainly stock application, but little that gives the brand vs breakdown temperature ratio.
I found out recently that TSC traveller brand gear oil has a very low life expectancy, and worse yet, breakdown temp when used in automotive drivetrains that endure what a daily driven vehicle would see that's been built with off-road use in mind.
In my exact application, everything except my engine uses gear oil. I don't know exactly what my late 70s NP435 and 205 could possibly get up to temperature wise. I'm to the understanding that a rear differential can climb to 200 degrees easily especially during break-in. What concerns me is I've heard that cheap off brand gear oils (TSC traveller) breakdown is at 120-ish and happens to be what I put in my rear diff. Rumor has it that name brand gear oils obtainable at parts stores withstand 180(?)
Any clarification is greatly appreciated.
I was pretty concerned with the temp of my dana 300 with 4:1 gears for a short period of time. After driving highway for extended periods of time I would pull infrared temps off of the case close to 200 degrees F. I always had plain lucas diff oil in it. My plan was to change the oil in it twice a year since the common consensus was that 200 deg is pretty warm for diff oil. I imagine np205 is probably going to be cooler since they are larger cases and they hold more oil.
 
I was pretty concerned with the temp of my dana 300 with 4:1 gears for a short period of time. After driving highway for extended periods of time I would pull infrared temps off of the case close to 200 degrees F. I always had plain lucas diff oil in it. My plan was to change the oil in it twice a year since the common consensus was that 200 deg is pretty warm for diff oil. I imagine np205 is probably going to be cooler since they are larger cases and they hold more oil.
What I recently found out about my 205 is that on long drives of 100+ miles, it would steadily weep out oil from the output seals. I've replaced the seal twice already. Once for each time I've broken a driveshaft. Each time I inspected the bearing and it always looked and felt fine to me. Typical procedure: I'd drive it 5 minutes to work and 9 hours later back home with minor detours. Moderate stop and go, 45 mph average. In that drive time, my engine temperature barely reaches 195 and my rear differential is warm to the touch, as to be expected. It was only on the longer trips pulling the boat or hauling my kayak/camping gear that I'd see the leak appear. I noticed the fluid looked "watery". Never dawned on my really. Then a mechanic friend told me that the cheap gear oil does break down at a cooler temperature than the higher quality does. Then it all kinda made sense.
It's one of those "why the hell did I not think of that?" sorta things.
 
Not any sort of tech guru but is it pushing past the seals due do initial breakdown stages from heat and the off-gasing is not being vented enough to cause it to weep from the weakest link (the seal)? Not saying that traveller is any better than it isn’t but what’s your t-case vent situation like? Asking just for the knowledge of being told I’m dum
 
I know guys that run 10w30 across the board in everything. Axles, motor, case, etc. (not the trans) and have had killer luck. I’ve not tried it, although I have been tempted seeing their success.
 
My thoughts.
Since most of us change our diff fluid sooner than most, the lower grade stuff would probably be sufficient most of the time. If you also DD your rig like @XJsavage then stepping up to a name brand like Lucas is best IMO. For a dedicated wheeling rig, I think you would be well served with lower grade stuff.
I run Lucas non-synthetic in everything personally. Even buying it at retail isn't much more than the house brand stuff.
 
Not any sort of tech guru but is it pushing past the seals due do initial breakdown stages from heat and the off-gasing is not being vented enough to cause it to weep from the weakest link (the seal)? Not saying that traveller is any better than it isn’t but what’s your t-case vent situation like? Asking just for the knowledge of being told I’m dum
5/16 hose barb, 5/16 oil cooler hose.
 
Adding on to this, does anyone have any personal experience with additives making a difference. I heard about bestline racing products on a podcast in the past, and it looks like something you could use in the gearbox and diffs to reduce heat. Pretty cool some of the experiments that people do with it. https://www.youtube.com/watch?v=m8ZKMCfAue4
I've always heard that with old manuals that adding atf does make for smoother shifts.
I can't comment on that from personal experience, but anytime I store anything, I do store full of atf for anti-corrosive purposes. Or to revive. I also run 40+ year old components.
 
I've always heard that with old manuals that adding atf does make for smoother shifts.
I can't comment on that from personal experience, but anytime I store anything, I do store full of atf for anti-corrosive purposes. Or to revive. I also run 40+ year old components.
That makes me feel better about an old bronco dana 20 I picked up a while back. It was full of atf and I was concerned.

Sent from my Pixel 2 using Tapatalk
 
That makes me feel better about an old bronco dana 20 I picked up a while back. It was full of atf and I was concerned.

Sent from my Pixel 2 using Tapatalk
Atf is a badass rust deterrent.
 
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