Right after I got my (new to me) 2005 Corvette, I had the dealer change the transmission fluid and the rear differential fluid. Within a day of having this service done, I started getting weird scrubbing and crunching noises in low speed, tight turns (like in the cul de sac at the end of my street). I checked the dealer invoice to see what diff oil they had used and it was GM part #88900401 full synthetic 75w90. I looked this up online and it is not a limited slip diff oil and there was nothing on the invoice to indicate that they had added any limited slip additive. I called the dealer about this and was told that 88900401 is the diff oil listed in their computer as the correct oil for a 2005 Corvette and no limited slip additive is needed. Okay, but what about this noise? They wanted me to bring the car in and leave it with them for a full day so they could diagnose the noise. I had an appointment for them to do that this past Friday and they were going to give me a loaner car gratis for the whole day.
However, earlier last week I did a lot of research about this online and I discovered 88900401 is NOT the correct fluid for C6 differentials. GM issued a TSB (#07-04-20-002A) in 2008 detailing this noise from the differential and specifying a new gear oil that was specifically developed to eliminate chatter from the clutch pack of the limited slip diff on the C6. The new oil is Dexron LS 75w90, GM part #88862624 and it's been the factory fill in all Vettes (C6 and C7) since the 2008 model year. So, long story short, I decided to forgo the appointment on Friday. I went to the dealer and bought three quarts of the Dexron LS ($26 a quart!) and had my local shop change it out. Noise gone. Problem solved.
So, if you have a C6 Vette and ever have any strange noises from your rear end, or just decide to change the diff oil as a preventative measure, be sure to use the Dexron LS, part #88862624.
However, earlier last week I did a lot of research about this online and I discovered 88900401 is NOT the correct fluid for C6 differentials. GM issued a TSB (#07-04-20-002A) in 2008 detailing this noise from the differential and specifying a new gear oil that was specifically developed to eliminate chatter from the clutch pack of the limited slip diff on the C6. The new oil is Dexron LS 75w90, GM part #88862624 and it's been the factory fill in all Vettes (C6 and C7) since the 2008 model year. So, long story short, I decided to forgo the appointment on Friday. I went to the dealer and bought three quarts of the Dexron LS ($26 a quart!) and had my local shop change it out. Noise gone. Problem solved.
So, if you have a C6 Vette and ever have any strange noises from your rear end, or just decide to change the diff oil as a preventative measure, be sure to use the Dexron LS, part #88862624.