Hornet1

I'm wondering why is it suggested to use different thickness in both diffs. Why not use the same oil for both diffs? Can you also explain the application of different thickness (on road, off road, track...) which oil would you use for these applications. Again, why two different oils in each diffs instead of using the same oil for both? I think my local hobby store suggested 5K and 7K (one was for the front the other for the rear). Which one is thicker, low # or higher # ex. 5K - 7K?

Any information would be greatly apreciated.
Thank you.

ed260z

The thicker the oil the less the diff wants to slip. 100K oil is almost like a diff locker. IMO unless your heavy into racing or rock climbing there is no need to use diff oil.
But if you do want to use it, you should also know that the thicker the oil, the wider your turning radius will be.
I use my truck for bashing around, and beating up Traxx's products. So I just use grease in mine.

Stablock

The higher the number, the thicker the oil.

Nitronutt

My Feedback: (2)

Most people use higher numbers (Just like engine oil - The higher the number, the thicker the oil and the less "diff action") in front and lower in the rear. I am not most people. I used 5k up front and 30,000 in the rear. I run mainly on asphalt and when I would turn sharp, my inside tires especially my inside front would lift off the ground and baloon. Basically, what that means is that you are losing power by putting it into the air or into the tire without traction. There would be nothing wrong with running the same oil in both. I plan to switch my rear to 5k on my next teardown. Oils are not very expensive, so expiriment untill you find what you are looking for.

You lhs is suggesting a good combo for general use - 7k front and 5k rear. Some racers go lower like 5kF and 3kR. It is all preference and how you want your truck to handle.

Like Ed said (Ha ha we agree again Ed!) the heavier the weight of oil, the wider the turning radius (Unless you can get the rear tires to power slide and therefore oversteer). Oversteer is very unlikely with the stock tires on pavement - Believe me, I've tried and tried and tried. When it is snowy, it is easy to slide and I can sometimes do it in the wet/rain. I really don't have any groomed dirt to try it on.

Try the 7kf 5kr and see if you like it. You can always change it.

cardriverx

I disagree with what ed260 said, diff oil really makes a difference. I just bash around so I chose 30k for the front and rear. I can now get over all most anything where as my truck would get stuck when it just had grease in it. Diff oil espically helps in snow, It gives it alot more traction. It just depends on how you use the truck, I would reccomend 30k for bashing and around 3 to 5k for racing.