I used valvoliine synthetic blend 5w-30 to change my engine oil. After draining my transmission, Can i use the same for my 5 speed getrag?

the old manuals back in the day called out 5w-30 for the getrag. But that was probably for conventional oil. Just wondering if synthetic blend makes a difference better or worse.

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87 GT Stock 2.8L

I ran mobil one in my 4 speed for years and it shifted smoother as soon as I put it in.

It won't hurt a thing.

quote Originally posted by gregr75: the old manuals back in the day called out 5w-30 for the getrag.

I'm not saying that what you wish to try is bad by any means... but you do realize that Synchromesh has been recommended by GM for a long time, right?

'88 Getrag syncromesh fluid
https://www.fiero.nl/forum/Forum2/HTML/148106.html

[This message has been edited by Vintage-Nut (edited 03-15-2025).]

I was using motor oil as per owner's manual.....then someone recommended the GM Synchromesh fluid- big improvement in shifting!

To give you an idea how good this fluid is, All of the Honda/Toyota/Subaru guys have switched to using it....

It is available from different manufacturers- Penzoil/Valvoline/Amsoil as well as AC/Delco who invented it.

quote Originally posted by cvxjet: I was using motor oil as per owner's manual.....then someone recommended the GM Synchromesh fluid- big improvement in shifting! To give you an idea how good this fluid is, All of the Honda/Toyota/Subaru guys have switched to using it.... It is available from different manufacturers- Penzoil/Valvoline/Amsoil as well as AC/Delco who invented it.

also mustang guys with the garbage 2013 6 speeds lol.
also word if warning this will cause rubber hoses to leak in certain honda models (the early 90s manual accords used the diff as a fluid pump into the steering rack to stiffen it at speed. they leak if you dont use 5-30 with a additive so just replace those lines)

quote word if warning this will cause rubber hoses to leak

Not True - Synchromesh fluid will not cause rubber hoses to leak.

Yes, the fluid is thin, and some has blamed the fluid when their seals started leaking, but the 'real' problem is old rubber....

I know synchromesh is better, but I have a small oozing external leak from my transmission… And because the stuff is lower viscosity, I'm afraid that leak may get worse.

not sure I want to try it until I get the transmission leak fixed.

The original GM spec was engine oil, some use 5w-30

Synchromesh is better for smoother shifting

Heavier oils can be a shifting issue during cold starts/weather...

quote I have a small oozing external leak from my transmission… And because the stuff is lower viscosity, I'm afraid that leak may get worse.

BTW - the molecules in synthetic oils are smaller than conventional oils

SO, going back to your question:

quote I used valvoliine synthetic blend 5w-30 to change my engine oil. After draining my transmission, Can i use the same for my 5 speed getrag?

You can, but if you're worried about synchromesh, then I believe you will be worried about Valvoline synthetic blend 5w-30 too...

Read more on PFF
https://www.fierosearch.com...trag&Action=DoSearch

[This message has been edited by Vintage-Nut (edited 03-16-2025).]