Chevy Tri Five Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
252 Posts
Discussion Starter · #1 ·
Has anyone swapped their straight 80-90 gear oil in their manual trans with synthetic? I was wondering if it's worth doing.

Pete
 

·
Premium Member
Joined
·
974 Posts
On Synthetic Oil

Has anyone swapped their straight 80-90 gear oil in their manual trans with synthetic? I was wondering if it's worth doing.

Pete
I am in the standard shift transmission business for more than 35 years. When this question came up about the fluid in standard shift transmissions I pretty well knew that General Motors engineers were correct with their research that heavy weight gear oil offered the best protection against gear breakage. But the quedtion keep coming up so I finnaly called Joe Liberty of Liberty Gear fame. They make standard shift trans for the NASCAR circut and others. (Google them for a real look at Standard shift trans technology)
Anyway at the time Joe Liberty had rebuilt as many Muncie trans as anyone in the country. He told me that one of the major causes of gear breakage was due to using fluid in them other than the reccomnended heavy wt gear oil, and that he had witnessed this first hand by checking the fluid in these trans as they had come into his shop.
Synthetic Oil offers little to no protection for gear breakage. Period and end of story.
 

·
Registered
Joined
·
770 Posts
what about a 1995 tremec t--56...i run penzoil snycromesh which is what i think is factory recommended?
 

·
Registered
Joined
·
252 Posts
Discussion Starter · #6 ·
Thank you all for the responses. I don't have an issue with trans/shifting troubles. Just trying to find out if there is better. So, what I'm going to do is drain and fill with synthetic and post what the difference is, if any.
Probably a couple of weeks before I can get on a lift.

Pete
 

·
Registered
Joined
·
3,437 Posts
Thank you all for the responses. I don't have an issue with trans/shifting troubles. Just trying to find out if there is better. So, what I'm going to do is drain and fill with synthetic and post what the difference is, if any.
Probably a couple of weeks before I can get on a lift.

Pete
Synthetic is not better for transmissions or rear ends, I've went the other way on all of mine. My Dad and I lost bearings in PU rear ends at less than 100k miles, Brother lost bearing in a PU 5 speed at 105K, never had that with 90 wt. We might lose a fraction of a mile per gallon when it's cold weather because it's heavier, but in CA it's not an issue.
 
1 - 7 of 7 Posts
Top