Question: Replace tranny fluid with syn 5w30 in T-case

[CHYKYNLIPS]

This has been argued both ways. Spec is 2 qt. of transmission fluid. Some say fill to 3 qt of full syn 5w20 or 5w30 motor oil by filling from speed sensor hole.

This subject may be like discussing the best oil brand or somthing like that but i wanted to do the swap until many chimed in warning not to and keep it spec because there are reasons gm specified trans fluid in there.....whats your opinion? Any mechanics have a legitimate mechanical reason to support either way?

 

[PhilsLB7]

I believe 5w30 is what Mike L. recommends.

 

[CHYKYNLIPS]

Right, but i was curious what evidence the people have that strongly disagree with doing it. I think it was on DF but there was mention of the lubrication system not being designed for the thicker fluid and that the tc inturn will not be properly lubricated. If its just a slinging type of pump then the higher level could cause the fluid to not be properly "slung" and if it was a pump then there was doubt it will function properly with a thicker fluid that it was not designed for.

 

[BombDocDiesel]

Mine has been fine for 30K.

 

[hondarider552]

I have had motor oil in my tcase sicne I had mike build my trans, over 45k miles ago. the DP "experts" can think what they want.

 

[CHYKYNLIPS]

Yeah, i have always thought syn motor oil would be a better protectant. When there is strong opposition to an idea, its natural for me to question it at first. I will probably do mine soon since i am in the process of changing out all fluid. One guy said it quieted his down but i cant hear noises like some people can.

 

[hondarider552]

Once I put the motor oil in mine I went to the track that night and it shifted in and out of 4hi-2hi easier and no clunking. Disengaged from 100mph nicely as well.

 

[05' Ditry Duramax]

So 2qts or 3qts?

 

[hondarider552]

3 quarts.

 

[05' Ditry Duramax]

Gotcha