mixing tranny fluid types

[jaansu]

I have some 7-8 year old Dexron III Mercon transmission oil, both from Proline and Castrol. I just went out and bought 3 qts of Castrol Dexron VI oil in preparation for changing the transmission oil in my 90 Camry. I was surprised how expensive it was and only available in quarts. Am I crazy to save a few bucks by using up this half gal of the Dexron III oil along with the VI oil? Is old oil possibly degraded? I believe it is acceptable to mix Dexron grades of oil but I'm wondering if the Mercon label means something different. Thanks.

[Grego 92]

I can't answer your question directly, because I don't know.

But, in case someone more knowledgeable says the oil is still good, you might consider using the older stuff to flush your power steering fluid and not mix it with the newer stuff. It uses Dexron III also.