8 speed gear oil

[bo dawg 516]

Does every one use 90-140 oil in the 8 speed rear ends or a different weight? 

[Racinbob 11,081]

I've used this in all my 3/4 and 6/8 speeds for decades. 

 

[ebinmaine 67,506]

I use whatever is the least expensive 75, 80, 90, up to 140 that's available. GL4 or GL5 shouldn't matter because there are no brass parts in these Transmissions.

 

The only issue that I will point out is, when it's real cold, Trina has a six-speed that is pretty temperamental. It has 85W140.  That'll be changed for a lower viscosity.

 

I use the same thing in my 8-speed c160 and have no issues.

[bo dawg 516]

yea I always thought the 90-140 was too heavy. I was thinking last time I changed one I used the 80-90 stuff.

 

[ebinmaine 67,506]

3 minutes ago, bo dawg said:

yea I always thought the 90-140 was too heavy. I was thinking last time I changed one I used the 80-90 stuff.

 

 

On Trina's lighter tractor it makes the machine act like it's in low low unless it's warmed up a little bit. I figure the reason it seems okay in my bigger heavier machine is that the extra weight of the tractor compensates for whatever push the oil is trying to give.

[bo dawg 516]

I had the Lucas 80-90 and used that.

 

[squonk 41,118]

Back in the day WH used ( I think) 40 wt. motor oil. I remember as a kid draining the trans oil out of our 604 and putting in 90wt. The next winter you had to have that Tecky warmed up and singing before letting the clutch out in neutral to warm up the trans. 

[ebinmaine 67,506]

57 minutes ago, squonk said:

Back in the day WH used ( I think) 40 wt. motor oil

 

Correct. 

 

 

57 minutes ago, squonk said:

draining the trans oil out of our 604 and putting in 90wt

 

40 Weight engine oil has the same viscosity as either 75W or 80W gear oil. 

The extra 10 to 15 wouldn't seem like much but it would certainly make a difference. 

 

 

[Maxwell-8 4,275]

1 hour ago, squonk said:

Back in the day WH used ( I think) 40 wt. motor oil. I remember as a kid draining the trans oil out of our 604 and putting in 90wt. The next winter you had to have that Tecky warmed up and singing before letting the clutch out in neutral to warm up the trans. 

Viscosity for motor oil is differently measured then for trans oil.  30wt motor oil has the same viscosity as transmission oil 80wt

40wt motor is somewhere between 80wt and 90wt trans.

 

[Racinbob 11,081]

Wheel Horse issued a technical service bulletin calling for a switch to 40w in the early 60's when they first started using the two piece transmission cases. It was in hopes of alleviating the 'suctioning' effect that the shift rails caused. A very short time later they came up with a better fix in the form of flats on the shift rails, a deeper neutral detent combined with a 3/4" stop pin vs the previous 11/16" (another TSB). The 40w was overlooked in the owners manuals for a bit. 

The reality is that so many of these transmissions have survived years running with watered down sludge keeping them lubricated that you can just choose whatever oil/lube you want and you'll be fine. I'm not endorsing the watered down sludge though. 

[JoeM 7,874]

There are all kind of thought when it comes to oil in gearboxes. Of course the 80-90 has the kind of anti wear additive, or extreme pressure additives and allows good even flow and sling per say. 

 

I can remember at work having a large gearbox, close to 200K in cost, suffering from an internal leak between the hydraulic circuit and gear compartment. The hydraulic seals had a slight bypass into the gear area. Not having a spare ready and production behind, a decision was necessary. Of course it landed in my lap. Run it with diluted gear oil or shut it down and loose weeks of production. None of the oil and gear engineers would even want to discuss it. They error on the safe side of turn it off. I knew the hydraulic oil had some mighty fine anti wear additives but not so much extreme pressure.

Ran it 4 months draining out 10 gallons every morning and refilling with gear oil. Upon rebuild inspection, the gearing looked good as new. 

 

The same boxes spec heaver gear oil at first then it was reduced to the next level thinner. The lubrication and cooling of the internals was the reason.

 

So, I fill 80W-90 is the spec, going to a heaver oil of 90w-140 might not improve anything. 

 

If your looking to spend more on oil, and get some bang for the buck, go semi synthetic or full synthetic. The synthetics transfer heat so much much better. 

[squonk 41,118]

4 minutes ago, JoeM said:

The synthetics transfer heat so much much better. 

That's why I use Mobil 1 in my Hydro's that take motor oil.