Alot of questions for rc car oil

[1999fd]

Which would be better for a short cross truck stock is 550 would 650 be better?

What are these oils used for?

Extra Question:
What is black grease and why is it used for?

Got all of these for 4 dollars I wanna use them form my Senton 3s.

 

[gotnitro]

First 2 are for your shocks, 55wt and 65wt, second 2 are diff fluids, black grease is for your ring and pinion inside the F&R diffs.

 

[Sandracer_NL]

550 and 650 are shock oils. I'd give 550 a try first and see if you like it. Lighter shock oil dampens the shock recoil a bit, but I don't think you'll notice a significant difference between 550 and 650 when just bashing.

The 5000 and 7000 are for diffs. For buggies a 5k/7k/5k (front/cener/rear) could be a setup, but it also depends on your linking and terrain. Some say the bumpier the terrain the lighter the oils, but you can diff out more. The heavier the center diff oil, the more power gets distributed between front and rear (, the heavier in the front and rear, the more power distribution between left and right.

The black grease you can use for diff gerars and o-rings.

 

[1999fd]

550 and 650 are shock oils. I'd give 550 a try first and see if you like it. Lighter shock oil dampens the shock recoil a bit, but I don't think you'll notice a significant difference between 550 and 650 when just bashing.

The 5000 and 7000 are for diffs. For buggies a 5k/7k/5k (front/cener/rear) could be a setup, but it also depends on your linking and terrain. Some say the bumpier the terrain the lighter the oils, but you can diff out more. The heavier the center diff oil, the more power gets distributed between front and rear (, the heavier in the front and rear, the more power distribution between left and right.

The black grease you can use for diff gerars and o-rings.

Will that oil work for a plastic Senton diff or will the gears stop spinning?

 

[Hector_Fisher]

Those are the oils that come in tekno kits. Those should be pretty good quality.

The black grease is used for gears and shafts like this picture from my tekno SCT manual

I suspect the black grease is probably plastic safe, since it would contact plastic parts in the tekno build.

Keep in mind, unless you use a very thick grease, most everything you put on the diff gears will be flung off very quickly after you start driving.

 

[Hector_Fisher]

Will that oil work for a plastic Senton diff or will the gears stop spinning?

Use a plastic safe grease. The pictures you show are for oils, which are used in the differential.

Something like these or similar:
https://www.amazon.com/Super-Lube-92003-Lubricating-Translucent/dp/B0081JE0OO/
https://www.amazon.com/Lucas-Oil-10574-Tacky-GREASE/dp/B0049SUK5Y/