6 speed
Race Director
Joined: Oct 2005
Posts: 11,770
Likes: 175
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Team Owner
Joined: Aug 2005
Posts: 34,988
Likes: 515
From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09 thru '20
Thread Starter
Pro
Joined: Oct 2011
Posts: 703
Likes: 76
From: leesburg fl
St. Jude Donor '12
Thanks for all the help guys, I just finished changing the trans fluid and all went well. Now I see that the under side of my car needs a good cleaning. Im glad I changed the fluid the plugs showed no sign of anyone ever putting a wrench on them. And yes I did the fill plug first. Thanks again
Thread Starter
Pro
Joined: Oct 2011
Posts: 703
Likes: 76
From: leesburg fl
St. Jude Donor '12
My 6 speed shifts smoother after changing the fluid. It was not to bad it just took a little push and sometimes I had to let the clutch out a little to put it in first. Not now its like brand new money, Now I will change the rear oil. Do I need the GM posi lube with amsoil?
I will flush the cooling system this weekend also, Any good tips on doing that, I've done a lot of cars in the past but never a C-4
I will flush the cooling system this weekend also, Any good tips on doing that, I've done a lot of cars in the past but never a C-4
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
The AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT) comes with friction modifier already in it and you do not need extra additive to prevent diff chatter in the C4 or C5 diff. Note that GM changed the diff clutch plates in the C6 and the C6 needs more additive than the C4/C5 diffs. But, for your C4 - what's in the AMSOIL Severe Gear is enough.
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C66 Racing #66 NASA ST2, SCCA T2
AMSOIL Dealer (Forum Vendor)
AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
Le Mans Master
Joined: Oct 2007
Posts: 9,682
Likes: 3,434
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
The AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT) comes with friction modifier already in it and you do not need extra additive to prevent diff chatter in the C4 or C5 diff. Note that GM changed the diff clutch plates in the C6 and the C6 needs more additive than the C4/C5 diffs. But, for your C4 - what's in the AMSOIL Severe Gear is enough.
That is the fluid I use in my '90 and I never had any chatter during street driving.
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