transmission grinds

[93turbomr2]

on my 93 turbo mr2 i have been getting a small amount of grinding when shifting into 4thand 5th only.thought it was probally the syncros.so just recently i replaced the tranny fluid with full synthetic mobile1 75/90.after the replacment the gear box seemed smother and did not grind for say 10 minutes.once the car warmed up though it began doing the same thing again.does anybody know if this sythetic fluid will help my problem with time.or am i just pissing in the wind with the new fluid?i have only drove the car about 15 miles with the new fluid.

[MitchB]

That oil is a good try, but a much more proven oil is Synchromesh. Proven in that MANY people have used it in their cars of all makes, and it makes those synchros work SO MUCH better. (Yes, it did on my MR2 as well. And I drained out Redline MT-90 to put it in.)

Most folks know it as GM Synchromesh because GM made the spec for it years ago. There are now numerous products that meet the same spec, and hence, use the word Synchromesh in their product names. GM Synchromesh is available from GM dealers with a list price of $9.91/liter. OTOH Pennzoil Synchromesh is $4.99/quart at Autozone.

[93turbomr2]

will the syncro mesh provide sufficent protection for the transmission?do you fill the tranny completely with this product.would you drain the new tranny fluid i just added right away or give it some time to see if it helps?

[MitchB]

There is a LOT of debate about the "proper" protection for the tranny. MANY people, with MANY different types of cars have successfully used Synchromesh.

Also, if it helps, your tranny is essentially on it's way out, but it has been YEARS and THOUSANDS of miles since new. If it didn't last another ten years because the oil wasn't perfect, would it really matter?