tranny fluid
Ultimate HDF Member
Joined: Mar 2008
Posts: 5,788
Likes: 203
From: SW Florida
After reading though most of this thread (three years worth of info), I have chosen to use Spectro Heavy Duty Platinum 6-speed Transmission Oil. It just arrived today and I will be changing it soon at the 5000 mile service. I also purchased there Heavy Duty Primary Chaincase Oil. The transmission fluid is a bit pricey, but If it's good enough for Baker, it's good enough for me. 
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
Use any brand heavy gear oil (75w140 or higher), preferably synthetic. I've used Royal Purple 85w140 and Redline Shockproof Heavy 75w250 and can't tell the difference between them in my '07 SG with IDS. Both quietened the tranny a bit compared to 75w90 that I ran for about 4k early on.
I used 75w90 in my '96 RK and never had any trouble in >100k miles, but based on my experience the 6-speed is noisier and can benefit from a heavier fluid.
I used 75w90 in my '96 RK and never had any trouble in >100k miles, but based on my experience the 6-speed is noisier and can benefit from a heavier fluid.
Seasoned HDF Member
Joined: Apr 2008
Posts: 8,051
Likes: 50
From: Florence, MT (Bitterroot Valley)
I can't believe I'm the only one here using Redline Heavy Duty Shockproof in my gearbox. There isn't anything that could get me to change. I've got at least 250,000 miles on various HD's with it in the Trans, and haven't had a problem yet.. So, I guess I'll just stick with what works, and works, and keeps on workin'...
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Ultimate HDF Member
Joined: Mar 2008
Posts: 5,788
Likes: 203
From: SW Florida
I can't believe I'm the only one here using Redline Heavy Duty Shockproof in my gearbox. There isn't anything that could get me to change. I've got at least 250,000 miles on various HD's with it in the Trans, and haven't had a problem yet.. So, I guess I'll just stick with what works, and works, and keeps on workin'...
