GASHOG.....50wt 65-72...80-90wt 73-86, so what changed, the oil or the trans design???

 

Interesting topic. I'm planning to change my NP435 from 80W90 to synthetic 75W90 soon, maybe tomorrow.

Gashog, I was under the impression that the NP435 syncros were bronze? Is this not correct.....? I do however run GL-5 in it, and in fact the synthetic I plan to use is GL-5.

The linked article states that GL-5 should not be used because the EP additives plate the metal (under high heat) and impede oil flow. I think that's an old article, because today's GL-5's are buffered to prevent this from happening, even on yellow metals.

I'll post back on how it shifts with the new synthetic.

 

awesome, i want to hear how the synthetic works

 

My 70 F-250 4x4 has the original sticker inside the glovebox door that reads " after transmission break in fill with 50 wt non-detergent motor oil". After I saw that sticker I tracked down some non-detergent 50 wt racing oil, put it in the tranny and it ate itself in 200 miles. I ran 80-90 in the new tranny and never had an issue with it. Now the NV4500 takes Castrol Syntorq. Spendy stuff, but that NV shifts like silk.

 

Well I finally got my NP435 changed over to synthetic this afternoon. I used Valvoline 75W90. Haven't had a chance to drive it much yet, but so far it shifts great.
AverageF250, that's how I'd describe mine; it seems to slip into gear easier with the syn. The real test will be on a cold morning when the oil's stiff, but so far so good.....

 

I see way too many cars and trucks with the same factory oil in the transfer case, transmission, power steering, brakes, and axles.

I always spread the word to people that it is wise to change those fluid regularly. Sure it takes time and money to change the fluids, but it cheaper than replacing those parts.

 

how much did that valvoline synthetic run you lone ranger???

 

Kubota, I've had the Valvoline sitting on the shelf since last fall, and I don't remember exactly; I'm thinking $8-9/qt. I'll let you know for sure Sat, since I'm about a pint low and need some more.

I do remember that the 75W90 was lots cheaper than the 75W140.

 

If you live in a cold winter climate zone take your 75-90 or 80-90 and add 4 ounces of Honda Motorcycle Racing transmission oil with you gear oil. It looks about 15 to 20 wt, has anti foam and high shear protection for gear faces. Ran this combination mix for 843K hard miles in a 435 box.

.....=o&o>.....

 

When I had my 435/205 combo the way I used the truck the majority of the time the tranny and t-case had river water/75-90 gear oil in them, never had a problem with either one

 

Beemer, is this a typo? That's remarkable mileage if it's 843,000 miles. The Honda Racing gear oil must be good stuff.

PepBoys didn't have Valvoline, so I picked up a quart of Mobil 1 75W90 for $9.99 today. Oil prices seem to have creeped up since last fall, when I bought the Valvoline.

I had a chance to drive the Bronco more today, with the synthetic in it, and the difference was very noticeable. The trans goes into gear much better, with a 'snick-snick' rather than a 'grrr-grrr', if that makes any sense. It's much smoother. I wish I'd changed it over years ago.....

Brian460, how did yours shift with the 75W90? (Never mind about the river water.)

 

Nope, 843K is correct, the 360 went 472K with 2 valve jobs, timing chains, oil pump, one set of rod and main bearings rolled in. Built up a 414 and ran it until 843K. A quick hone then ringed the old 360 and reinstalled. Sold truck 7 years ago, it's still running with unknown miles now on the NP and old 360.
The NP was worn in the case so I made custom cluster thrust washers after milling the case, new synchros, # 308L 11 ball bearing for the 7th time and new shifter top. When I beat the snot out the box that 308L bearing would fail every time. The 414 would of shortened that boxes life considerably, the 435 I don't consider as "a bullet proof box" in my book (no flame wars please).
With straight 50wt motor oil bearings failed sooner, 80-90 a little stiff shifting in cold mornings but bearings lasted longer so hence the Honda oil thinner.

.....=o&o>.....

 

Ok...so in summary....would the following be good choices?

DANA 60 Rear - 80w90
DANA 44 Front - 80w90
NP435 - 80w90
NP205 - 50wt or 30wt or 80w90 gear oil?

 

With your location were you'll get below 40-45 degrees Fahrenheit like winter coming up it will be hard shifting in the 435 box in the mornings. To use 50 wt motor oil that was an option vs 90 wt you will loose the extreme pressure protection properties of sulfur base oils. Where I live in a warmer climate even when it dropped to the low 40's the 435 shifted hard until the box warmed up a bit. I added 6 to 8 ounces of Honda's racing motorcyle oil which feels like a 20 wt before topping off with 80/90 wt on a tranny oil change. This oil has high shear, anti foam and oxidation protection for the gear faces. I ran this blend over 843K miles in the 435, new owner now at 940K, mind you I have replaced bearings and synchros, shifter top but no gears.
For the 203/205 use what manufacture recommends.
Stay away from 140 wt in the axles as your fuel mileage will go down.

.....=o&o>.....

 

I'm really impressed with the 75W90 synthetic in my NP435. It's been in there most of the summer now, and it shifts great. The synthetic is slightly thinner at cold temperatures than the 80W90, so it might do better in winter. Guess I'll find out in a few months.....