The Stovebolt Site Forums The Shop Area Engine Shop Multi viscosity tranny lube, good or bad idea?

I was thinking of changing the 4 speed tranny lube in my 46 1/2t.I wanted to put some sort of Lucus oil treatment to get the oil to climb the gears and going with a 85-140 gear oil. Any body with more experience than me can teach me is this a good idea or bad.

Rick.........

I dont know about the Lucas treatment but the multi- viscosity lube is a good idea.

Multi-vis is almost always better. It starts out thinner, and gets thicker as it heats up, 180 degrees opposite for standard oils. They flow slowly when you first start and reduce in effectiveness as the temps climb. Multis give you initial flow, and then better protection as they heat up!

blackjack62,

Are you sure it 'gets thicker as it heats up'. How is this done I wonder. My bet would be it 'doesn't thin out as much' when it heats up! I know how that's done.

Stuart

Oil does not thicken as it heats up. All conventional oils thin out some as they heat up. The multi viscosiy oil has additives so that at the higher test temperature it is no thinner than the straight oil of the same number.

What truckernix said. Lucas oil stabilizer is a viscosity enhancing additive making the oil "stickier" for it to cling to the gear more. The stuff works well with petroleum based products. I would not use it with synthetic as the synthetic (Mobil 1, Red Line, etc.) already have viscosity stabilizers in them. I myself switched to Mobil 1 trans lube a cumulative 750k miles ago and will continue to switch all my transmissions, differentials and transfer cases to it.

Apparently, oil that is rated @ 5w30 (multi-vis) is in fact 5w oil, that contains an additive which makes it act as if it's 30w when it reaches operating temps. It does'nt "get thicker" as it heats up, it "Acts" thicker when it reaches operating temps. I remember when I went to Harley tech school, There was a seminar by a Valvoline rep, where he explained this in detail. If multi-vis oil got thinner when it got hot, there would be no reason to label it " multi-vis." Straight wheight oils start out at the rated viscosity, and drop from there as the temps climb. Multi-vis oils start @ the lowest rating, and rise to the higher rating when they reach operating temps.

Check this page out.

http://www.blackstone-labs.com/oil_viscosity.html

Here's another page which is a bit more picky about wording. They say an an"oil manufacter" (apparently unamed) says that theres no such thing as multi viscosity oil. Multi grade oil is oil that flows like the lower rating at cold temps, and like the higher rating at high temps. Like everything else it's complicated, but suffice it to say, the point of Multi-GRADE oils is they flow well when cold, but still provide the protection at elevated temps!

Valvoline: http://www.valvoline.com/carcare/articleviewer.asp?pg=ccr20040601ov

A 70/30 mix of Lucas synthetic gear oil and the Lucas stabilizer has worked very well in my 3 speed/overdrive.