It costs $9. I also found that I put in 2 bottles of the 946 ml oil (75w90), so almost 1900 ml total, and it did not start dripping out of the top of the fill hole. I did not add any more oil! GM says it calls for 1.6 litres only, so it turns out I put. Looking to change rear axle fluid this holiday weekend. I started to have some chatter in the rear end and was told it was time to change rear had a hum to it so I removed the synthetic and used a standard gear oil and You need thicker dyno oils to protect heavy loads, but wont work in high altitude.