Valvoline Synpower

[xcracer]

My questions are this:Any feedback on valvoline synpower(full synthetic) gearoil 75w-90 for the rear and TransX posi-trac limited slip gear oil additive. They meet all the required specs. and I'm curious if there have been any bad feedback from these products.



My truck is a 98. 5 24v,nv4500,3. 54 LSD,stock,28k miles.





First diff. gearoil change. I tow about 5000 miles a year,a 7k RV T. T.

 

[Archive]

Jenright,

I used the 75w-90 Synpower in my 4:10 limited slip differential and did in fact end up needing the additive to stop a mild case of the "chatters". I ran about 15,000 trouble free miles with the Valvoline Synpower lube.

I decided while pulling my trailer one HOT day to switch over to the 80w-140 synthetic lube that Daimler recommends for extended towing in hot climates. My trailer weighs 8500lbs, and I have a Bombed engine, so I wanted the peace of mind from the heavier gear lube. I bought the Red Line brand thru the Summit mail order catalog at $7. 95 a quart. I couldn't find anyone selling a full synthetic 80w-140 gear lubricant locally. I hope that more trailerist will post they're own experiences and opinions on this topic. I'm right at 40,000 miles so far.

BTW, no "chatter" using the heavier lube without the friction modifier. (10,000 miles)

 

[WadePatton]

I just filled mine with the Valvoline Synthetic

Now to go play with the modifier. Results in a day or two.



BTW my LSD worked fine before.

[edit after test drive]

No chatter, LSD working fine, ZERO additive. I suppose there was enough residual friction modifier in the rear assembly coupled with the properties of Synpower to keep the clutches happy. I'll keep additive on board in case the need arises.

 

[SRehberg]

I'm in the process of getting ready to change my diff oil to synthetic, but have stopped short due to a post in another forum stating loss of LS action when the synthetic was installed. The author mentioned everyone thinks their rearend is o. k. when it isn't making any noise/chatter after the lube install, when in fact it is to slippery for the LS clutches to work. He had to back up and use the "blend" by Valvoline so the LS function would work. Obviously many wrote back stating their units worked just fine with the synthetic, but his counterpoint was, "how do you know?" Without slippery surfaces to try it on or just "smoking" the tires, it is almost impossible to tell if the unit is performing correctly.



Now I realize the manufacturer wants full synthetic for trailer pulling, and I had planned to do just that, but I don't want to lose my LS ability. Anyone had any experience along this line?

 

[WadePatton]

When I "test drive" a LSD, I do full-lock turns on asphalt, then drop a tire in the dirt/grass/mud and spin, put in all dirt/grass/mud and spin and of course light 'em up on asphalt.



Works fine. The Valvoline synthetic hasn't been in long but has passed all those tests so far. I'll report if anything changes.



YES you probably WILL lose LSD action if you dump 7 friggin OZ. of friction modifier in the diff. (Per DC and the additive bottle. )



START with ZERO. If chatters, add 1 or 2 oz. at a time until chatter goes away. Then test like I do.

 

[SRehberg]

Good point for the additive, and that's how I'll treat it. If it doesn't need the additive, then I'll leave it alone, but if it does, then I'll go an ounce at a time. Thanks for the "hands on" report. I want the rearend to last as long as it can.