Manual transmission fluid type?

1988 CHEVROLET SILVERADO
218,500 MILES • V8 • 4WD • MANUAL
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CHARLIEK920
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  • 1 POST
I drive a 88' silverado and my transmission is leaking. I plan to get it repaired, but until I have the money Firestone suggested I put 5W30 oil into the fill port to keep from further damaging it. They said to pour the oil into the fill port until it overflows. The problem is I cannot find the fill port. If you could help that would be great. Thanks!
Dec 9, 2009 at 7:40 PM
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JACOBANDNICKOLAS
  • ✓ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
DO NOT MIX 10W30 with the gear lube in the trans.

If you have a 5 speed, it uses GM part #1052931. I believe that is a synthetic type gear lube. If it is a 4 speed, it takes GL-5 80W or 80W90.

If you add motor oil, I have no idea what the viscoisity will be and it could cause more damage.

Let me know what the transmission is doing so I can better help you.

Joe
Dec 18, 2020 at 9:01 AM
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