Manual transmission fluid type?

Tiny
CHARLIEK920
  • MEMBER
  • 1988 CHEVROLET SILVERADO
  • V8
  • 4WD
  • MANUAL
  • 218,500 MILES
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!
Wednesday, December 9th, 2009 AT 7:40 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
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
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Friday, December 18th, 2020 AT 9:01 AM

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