Hi all,

I just found that I added 75w-90 instead 75w-140 to transfer case. Is it a big problem? Thanks very much.

Ran

 

Yup. I would change it ASAP.

 

yeeran, are you going to trash your transfer case if you drive it, I don't think so. can you do long term damage, very possible. Granted, I used 75W-90 in the rear end of my Ford truck when it called for 75W-140 (both were full synthetic) and I didn't see any additional wear on the gears over time. So, what it can do to the transfer case is hard to say.

At highway temps, the lube is going to perform pretty much the same since both lubes have the same thickness at temp. It is when the transfer case is cold that you are going to "see" the different lubricating properties.

 

Thanks for your inputs.

I will change it right now after driving about 15 miles.

Thermo,

I guess 75w-90 and 75w-140 have the same properties at low temperature, right? Since both of them have 75W. Sorry if I am wrong. I am new to car.

 

yeeran, just the opposite. At operating temperatures, they will have the same characteristics since the first number is the thickness of the oil when it is hot. The second number is the thickness of the oil when it is cold. The 90W oil is going to be thinner than the 140W oil.

 

Also, make sure you use a GL-5 specific gear oil in your transfer case (and differential, too). GL-4 is for manual transmissions. The difference between the two specs is that GL-5 is for gears that are subject to higher pressures than would be found in a manual transmission. See the conclusion section, here: AMSOIL Article - Gear Oil Basics

And you do not need a gear oil that includes sulfurous limited-slip friction-modifier differential additives. I can't find a reference at the moment, but I distinctly recall reading (perhaps on Redline Oil's web site) that such additives can do damage to bronze and brass parts such as those commonly found in manual transmission synchronizer bearings. Those additives aren't necessary for our cars, since they don't use a clutch-type limited-slip differential. So I'd just as soon avoid using a product that contains the additives. If you're not sure, just get a whiff of the oil that you're using - if it stinks like something died in the bottle three years ago, it probably contains the additives!

 

rothe, the sulfurous additives are meant more for the rear differentials of trucks that have limited slip units installed in them. Like you mention, those fluids are not necessary in our applications as we don't have anything that operates on those principles. That way you are garanteed to have more oil where you need the oil, not some additive.

 

Are you sure Chris?

It was always my understanding that the first number was the cold viscosity and the second the hot.

 

Norri, you are correct. I got the numbers mixed up in my head. Granted, I need to go back and do some more looking into this as I would think when you heat up the oil/lube, it would get thinner and therefore flow through the orifice for testing faster, leading to a lower viscosity. But, in the quick reading, it may be a relationship thing, not a physical property thing (hence where my confusion came in).

 

Thanks to all.

I used Royal Purple gear oil which is recommended in many posts here.

 

Autovip - how to tilt a car .... - YouTube

Do not need to swap tube and plug if we have this...

 

That's correct.