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I'll be changing the diff oil in my 2009 LS3 with auto trans for the first time myself. I can choose 3 or 4 different brands of LS (limited slip) gear oil for this job. Should I stick with the factory AC Delco Dexron brand 75-90w, or try Mobil One or Valvoline? Mobil One states it is synthetic, the other two don't say.
I can tell you from experience, that Dexron is the way to go. It has the friction modifier that works. I tried Redline, which guys that race and motocross use, but that stuff was thick, and even with the added modifier, I could not get the differential to quiet down, no matter how many figure 8's I did. I tried it for 2 weeks, then decided to drain that stuff, flush it with Dexron, then topped it up with the good stuff, and a few figure 8's and quiet as a church mouse. I had to ask myself after this experience , why try something that may or may not be as good as the recommended fluid?
I did the differential oil change in my '09 C6. I ended up using Mobil 1 gear oil with the LS additive and synthetic formulation. My decision was made for me when at the local Pep Boys. They're going out of business and becoming Advanced Auto very soon. The Mobil 1 was on clearance for just $7 a quart, and I needed 3. Anyway all went well using a 10mm allen socket head on my 3/8" drive socket wrench. I suggest this over a regular allen wrench/key, with the short handle. I was easily able to remove the fill and drain bolts. I also flushed about half a bottle into the fill hole and let it drain out the bottom for a cleansing effect before plugging and topping off the diff. NOTE: some of the earlier year C6s have the drain & fill plugs awkwardly located and will require some "angular tool adjustments." I still recommend doing this fairly simple maintenance yourself to save money and peace of mind. Lots of tutorials on this forum and YouTube
Which Differential Gear Oil?
